CN111141049A

CN111141049A - Cascade high temperature heat pump laboratory bench

Info

Publication number: CN111141049A
Application number: CN201911415884.6A
Authority: CN
Inventors: 刘洪鑫; 曹祥; 邵亮亮; 张春路
Original assignee: Tongji University
Current assignee: Tongji University
Priority date: 2019-12-31
Filing date: 2019-12-31
Publication date: 2020-05-12

Abstract

The invention relates to a cascade high-temperature heat pump experiment table, which comprises a high-temperature circulation, a low-temperature circulation, an air flow path, a chilled water flow path and a loop water flow path. Compared with the prior art, the cascade high-temperature heat pump experiment table adopts a unique variable capacity adjusting method, not only can realize the variable capacity adjustment of a heat pump system by unloading one compressor or closing the air injection enthalpy increasing function at a high temperature level, but also can realize the variable capacity adjustment of the heat pump system by the frequency conversion at a low temperature level, thereby accurately controlling the heat supply temperature of a heat pump; the design of an air duct without return air in the cascade high-temperature heat pump experiment table can realize heating at the temperature of more than 100 ℃; the design of loop water and air preheating and precooling coils in the cascade high-temperature heat pump experiment table can realize the preheating and precooling of air, reduce the load of a condenser and easily realize high-temperature heating at the temperature of more than 100 ℃; on the premise of not losing the system performance, the temperature in front of the valve is obviously reduced, so that the expansion valve is ensured to operate in a safe range.

Description

Cascade high temperature heat pump laboratory bench

Technical Field

The invention relates to a high-temperature heat pump experiment table, in particular to a cascade high-temperature heat pump experiment table.

Background

The heat pump technology is a new energy technology which attracts much attention all over the world in recent years, and can absorb heat from a low-temperature heat source to convert low-grade heat energy into high-grade heat energy so as to obtain more output heat energy than input energy.

The high-temperature heat pump collects heat in medium and low-temperature waste water and waste gas discharged and wasted by industrial enterprises through the high-temperature heat pump, converts the heat into high-temperature water or high-temperature steam, is used for industrial processes or heating, can directly replace a traditional coal-fired boiler, and is the best choice for realizing industrial energy conservation, consumption reduction and efficiency improvement.

A large number of comparison experiments are needed for the research on the heat pump cycle, and in order to facilitate the research on a heat pump system, various experiment tables are developed to realize operation experiments under different working conditions. At present, a heat pump system experiment table is mainly designed aiming at a single cycle, therefore, experiment tables with various cycles need to be built in the research process, and in the common high-temperature heat pump experiment table at present, a refrigerant absorbs heat from a low-grade water source or air source, adopts single-stage compression and is directly compressed to high pressure (the condensation temperature exceeds 100 ℃), the system pressure ratio is high, and the exhaust temperature is overhigh; heat is absorbed from the air, the temperature of a heat source is unstable, and the complexity of system control is increased; the high-temperature heat pump experiment table is mostly designed for fixed load, can only operate under the designed working condition, lacks a variable capacity adjusting method and cannot stably control the heat supply temperature; in addition, the tolerance temperature of the conventional electronic expansion valve on the market is only about 60 ℃, and if a conventional heat pump experiment table is adopted, the high supercooling degree is not easy to generate, and the temperature before the valve is over-limited.

Disclosure of Invention

The invention aims to overcome the defects in the prior art and provide a cascade high-temperature heat pump experiment table, which adopts constant-temperature chilled water (7 ℃) or cooling water (15-30 ℃) as a heat source, ensures that exhaust air has no safety hazard to the surrounding environment while heating at the temperature of more than 100 ℃ is realized through cascade circulation, and can realize variable capacity regulation of a heat pump system and accurately control the heat supply temperature of a heat pump.

The purpose of the invention can be realized by the following technical scheme:

the invention relates to a cascade high-temperature heat pump experiment table, which comprises a high-temperature circulation, a low-temperature circulation, an air flow path, a chilled water flow path and a loop water flow path;

the air flow path exchanges heat with high-temperature circulation through the condenser, then exchanges heat with the upstream position of the chilled water flow path through the air re-cooling coil, and finally discharges the air after heat exchange;

an air preheating coil and an air precooling coil are respectively arranged on the upstream side and the downstream side of the condenser;

the low-temperature circulation exchanges heat with the downstream position of the heat exchange chilled water flow path through the evaporator;

the low-temperature circulation exchanges heat with the high-temperature circulation through a condensing evaporator;

the loop water flow path is respectively connected into the air pre-cooling coil and the air pre-heating coil and exchanges heat with the air flow path.

Furthermore, the high-temperature cycle comprises two enhanced vapor injection compressors, a condenser, an economizer assembly, a gas-liquid separator and a liquid storage device which are connected in parallel;

the refrigerant absorbs heat from low-temperature circulation through a condensing evaporator and is gasified, then is mixed with the refrigerant gasified in a cooler in front of a valve, firstly enters a gas-liquid separator, is subjected to gas-liquid separation, is divided into two paths to respectively enter air suction ports of two enhanced vapor injection compressors, is compressed to an intermediate state, is then mixed with the refrigerant gas entering from air supplement ports of the two enhanced vapor injection compressors, is compressed for the second time, is changed into high-temperature and high-pressure refrigerant gas, is respectively discharged from air exhaust ports of the two enhanced vapor injection compressors and enters a condenser to heat an air flow path, then enters an economizer assembly through a liquid accumulator, and then flows back to the gas-liquid separator and the air supplement ports of the two enhanced vapor injection compressors through the economizer assembly to form high-temperature circulation.

Further, the high-temperature cycle also comprises an oil separator and an oil filter;

the oil separator is arranged between the exhaust port of the enhanced vapor injection compressor and the condenser, the high-temperature and high-pressure refrigerant discharged from the exhaust port of the enhanced vapor injection compressor is separated by the oil separator, and the separated lubricating oil flows back to the air suction ports of the two enhanced vapor injection compressors respectively after passing through the oil filter; the separated refrigerant flows into a condenser.

Further, the economizer assembly includes two economizers and a pre-valve cooler;

the refrigerant flows into the two economizers from the liquid storage device respectively and is cooled by low-temperature channels in the two economizers respectively, then the refrigerant is merged and flows into the cooler before the valve, so that the refrigerant is cooled to be below 60 ℃, and then the refrigerant flows back to the gas-liquid separator and the air supplementing ports of the two enhanced vapor injection compressors through 4 flow paths;

the first flow path passes through the low-temperature channel of one of the economizers and flows back to the air supplementing port of one of the enhanced vapor injection compressors;

the second flow path passes through the low-temperature channel of another economizer and flows back to the air supplementing port of another enhanced vapor injection compressor;

the third flow path flows into the condensing evaporator to exchange heat with low-temperature circulation;

the fourth flow path flows into the pre-valve cooler and flows back to the gas-liquid separator;

the first flow path and the second flow path are provided with electronic expansion valves on pipelines before flowing into the economizer;

an electronic expansion valve is arranged on a pipeline of the third flow path before flowing into the condensation evaporator;

a valve front cooler is arranged on a pipeline of the fourth flow path flowing into the gas-liquid separator;

two branch flow paths between the liquid storage device and the two economizers are respectively provided with an electromagnetic valve, and the unloading of a single compressor or the closing of the enhanced vapor injection function of any compressor is realized through the closing of the electromagnetic valves.

Further, the low-temperature cycle comprises an oil separator, a drying filter, an electronic expansion valve, a gas-liquid separator and a low-temperature compressor which are connected in sequence;

the low-temperature compressor is connected with the oil separator to form low-temperature circulation.

Further, the low-temperature compressor is a variable frequency compressor;

the low-temperature compressor can realize the variable capacity adjustment of a low-temperature stage by changing the rotating speed of the compressor, thereby realizing the variable capacity adjustment of the whole heat pump system and accurately controlling the air supply temperature of the heat pump.

Further, air flow path include the wind channel, the one end in wind channel be equipped with air intlet, the other end is equipped with air outlet, the wind channel in from air inlet end to air outlet end be equipped with air preheating coil pipe, condenser, air precooling coil pipe, air recooling coil pipe and fan in proper order.

Furthermore, the chilled water flow path comprises a chilled water pipe, and a chilled water pump is arranged between the chilled water inlet and the chilled water outlet;

the chilled water is pumped into the air re-cooling coil by the chilled water pump to exchange heat with the air flow path, and then flows into the evaporator to exchange heat with low-temperature circulation.

Furthermore, the chilled water flow path can be replaced by a cooling water flow path, the flow direction of the cooling water flow path is opposite to that of the chilled water flow path, and the temperature of the cooling water at the inlet is 15-30 ℃.

Furthermore, the cascade high-temperature heat pump experiment table also comprises a heat supply tail end;

the inlet of the heat supply end is connected with the outlet of the oil separator;

the outlet of the heat supply end is connected with the first flow path, the second flow path, the third flow path and the fourth flow path.

The following explains the detailed technical scheme and principle of the invention:

the high-temperature cycle comprises a high-temperature enhanced vapor injection compressor, a condenser, an economizer, a cooler before a valve, a condensation evaporator, a gas-liquid separator, an oil separator, a liquid storage device, an oil filter, a drying filter, an electronic expansion valve, an electromagnetic valve, a one-way valve, a refrigerant connecting pipe, an oil return pipe and the like; the low-temperature cycle includes a low-temperature compressor, an evaporator, a condensing evaporator, a gas-liquid separator, an oil filter, a drying filter, an electronic expansion valve, a refrigerant connection pipe, an oil return pipe, and the like.

The air flow path comprises an air inlet, an air preheating coil, a condenser, an air precooling coil, an air recooling coil, a fan, an air outlet, an air channel and the like.

The water flow path includes a chilled water (or cooling water) flow path and a loop water flow path. The chilled water flow path comprises a chilled water inlet, a chilled water pump, an air recooling coil, an evaporator, a chilled water outlet, a chilled water pipe and the like; the loop water flow path comprises an air preheating coil, an air precooling coil, a circulating water pump, an expansion tank, a water replenishing port, a circulating water pipe and the like.

Besides, a refrigerant flow path of the experiment table is provided with a refrigerant temperature sensor, a refrigerant pressure sensor and a refrigerant flowmeter, an air flow path is provided with an air temperature sensor and an anemometer, and a water flow path is provided with a water temperature sensor and a water flowmeter and used for testing system key parameters in the experiment.

High temperature cycle

The high-temperature compressor is two parallel-connected enhanced vapor injection compressors, and compared with a common compressor, the high-temperature compressor is provided with an air suction port and an air exhaust port and is additionally provided with an air supplement port. The air suction port is communicated with the gas-liquid separator through a refrigerant connecting pipe, the air supplementing port is communicated with the economizer through a refrigerant connecting pipe, and the air exhaust port is communicated with the check valve through a refrigerant connecting pipe. If single-stage compression is adopted, the pressure ratio is large, the exhaust temperature is too high, and two-stage compression can be realized by using the enhanced vapor injection compressor, so that the exhaust temperature is obviously reduced, and the heating capacity of the heat pump system is improved. Meanwhile, two parallel air injection enthalpy-increasing compressors are adopted, and the variable capacity adjustment of the heat pump system can be realized by unloading one compressor or closing the air injection enthalpy-increasing function.

The condenser is a refrigerant-air heat exchanger and is provided with a refrigerant channel and an air channel, and the condenser is of a common type such as a finned tube heat exchanger, a micro-channel heat exchanger and the like. The refrigerant channel of the condenser is communicated with the oil separator and the liquid storage device through a refrigerant connecting pipe, and the air channel of the condenser is communicated with the air preheating coil and the air pre-cooling coil through air pipes.

The economizer is a refrigerant-refrigerant heat exchanger and is provided with two refrigerant channels, and the economizer is of a common type such as a plate heat exchanger. The high-temperature channel inlet of the economizer is communicated with the electromagnetic valve through a refrigerant connecting pipe, and the high-temperature channel outlet is communicated with the cooler in front of the valve through the refrigerant connecting pipe; the inlet of the low-temperature channel of the economizer is communicated with the electronic expansion valve through a refrigerant connecting pipe, and the outlet of the low-temperature channel is communicated with the air supplement port of the enhanced vapor injection compressor through the refrigerant connecting pipe. The economizer can realize air supplement of the air supplement port of the compressor, can further increase the supercooling degree and reduce the temperature before the valve on the one hand.

The pre-valve cooler is a refrigerant-refrigerant heat exchanger and is provided with two refrigerant channels, and the pre-valve cooler is of a common type such as a plate heat exchanger. The high-temperature channel inlet of the cooler before the valve is communicated with the economizer through a refrigerant connecting pipe, and the high-temperature channel outlet is communicated with the drying filter through the refrigerant connecting pipe; the inlet of the low-temperature channel of the cooler before the valve is communicated with the electronic expansion valve through a refrigerant connecting pipe, and the outlet of the low-temperature channel is communicated with the gas-liquid separator through the refrigerant connecting pipe. The pre-valve cooler can further increase the supercooling degree to reduce the pre-valve temperature to below 60 ℃, and meanwhile, the low-temperature refrigerant channel of the pre-valve cooler and the refrigerant channel of the condensation evaporator are in parallel connection, so that the flow of part of the refrigerant passing through the condensation evaporator can be reduced, and the liquid separation of the refrigerant of the condensation evaporator is easier to realize.

The condensing evaporator is a refrigerant-refrigerant heat exchanger and is provided with two refrigerant channels, and the condensing evaporator is of a common type such as a plate heat exchanger and the like. Wherein, the inlet of the high-temperature channel (condensation side) of the condensation evaporator is communicated with the gas-liquid separator through a refrigerant connecting pipe, and the outlet of the high-temperature channel (condensation side) is communicated with the dry filter through the refrigerant connecting pipe; the inlet of the low-temperature channel (evaporation side) of the cooler in front of the valve is communicated with the electronic expansion valve through a refrigerant connecting pipe, and the outlet of the low-temperature channel is communicated with the gas-liquid separator through the refrigerant connecting pipe.

The gas-liquid separator has the functions of realizing gas-liquid separation, preventing the compressor from sucking gas and carrying liquid, avoiding damaging power parts of the compressor and playing a role in protecting the compressor. The inlet of the gas-liquid separator is communicated with the pre-valve cooler and the condensation evaporator through a refrigerant connecting pipe, and the outlet of the gas-liquid separator is communicated with the air suction port of the compressor through a refrigerant connecting pipe.

The oil separator is used for separating lubricating oil in high-pressure steam discharged by the compressor so as to ensure that the unit can safely and efficiently operate. The inlet of the oil separator is communicated with the one-way valve through a refrigerant connecting pipe, the refrigerant outlet is communicated with the condenser through the refrigerant connecting pipe, and the oil outlet is communicated with the oil filter through an oil return pipe.

The reservoir functions to accommodate charge volume changes under varying system loads. Wherein, the import of reservoir passes through refrigerant connecting pipe and condenser UNICOM, and the export passes through refrigerant connecting pipe and solenoid valve UNICOM.

The oil filter, the function is to filter the oil, keep the oil that flows back to the compressor clean. The inlet of the oil filter is communicated with the oil separator through an oil return pipe, and the outlet of the oil filter is communicated with an air suction port of the compressor through an oil return pipe and a refrigerant connecting pipe.

The drying filter has the function of filtering impurities in the refrigerant and preventing the impurities from entering the electronic expansion valve to block. The inlet of the drying filter is communicated with the cooler in front of the valve through a refrigerant connecting pipe, and the outlet of the drying filter is communicated with the electronic expansion valve through the refrigerant connecting pipe.

An electronic expansion valve is arranged in front of the economizer and has the function of adjusting the refrigerant flow of the economizer by controlling the superheat degree of an outlet; an electronic expansion valve is arranged in front of the pre-valve cooler and has the function of adjusting the refrigerant flow of the pre-valve cooler by controlling the superheat degree of an outlet; an electronic expansion valve is arranged in front of the condensing evaporator, and the function of the electronic expansion valve is to adjust the flow of the refrigerant of the condensing evaporator by controlling the superheat degree of an outlet.

The electromagnetic valve has the function of unloading or closing the enhanced vapor injection function of any compressor by a single compressor. Wherein, the import of solenoid valve passes through refrigerant connecting pipe and reservoir UNICOM, and the export passes through refrigerant connecting pipe and economic ware UNICOM.

The one-way valve is used for preventing the refrigerant from flowing back to the compressor after the compressor is stopped. The inlet of the one-way valve is communicated with the exhaust port of the high-temperature compressor through a refrigerant connecting pipe, and the outlet of the one-way valve is communicated with the oil separator through the refrigerant connecting pipe.

The working principle of the high-temperature cycle is that after the refrigerant in the condensation evaporator absorbs heat from a low-temperature stage and is gasified, the refrigerant is mixed with the low-temperature refrigerant gasified in the cooler in front of the valve and enters the gas-liquid separator together, after gas-liquid separation, the refrigerant is divided into two paths and enters the air suction ports of the two air injection enthalpy-increasing compressors respectively, and when the refrigerant gas is compressed to an intermediate state, the refrigerant gas is mixed with the refrigerant gas entering the air supplement port and is compressed for the second time to become the high-temperature high-pressure refrigerant gas. Then, the two paths of refrigerants flow through the one-way valve and then enter the oil separator, and lubricating oil in the two paths of refrigerants passes through the oil filter and returns to an air suction port of the compressor along an oil return pipe; the refrigerant enters the condenser to heat the air. And then, the refrigerant is divided into two paths after passing through the liquid storage device, respectively flows through the electromagnetic valves to enter the two economizers, is cooled by the refrigerant in the low-temperature channel, then is combined to enter the cooler before the valve, and is further cooled to below 60 ℃ (the temperature is lower than the tolerance temperature of the conventional electronic expansion valve). And then, the refrigerant is divided into four paths after passing through a drying filter, and enters two economizers, a pre-valve cooler and a condensation evaporator after passing through an electronic expansion valve respectively, so that the high-temperature circulation of the whole refrigerant is completed.

(II) Low temperature circulation

The low-temperature compressor is a variable-frequency compressor and is provided with an air suction port and an air exhaust port. The air suction port is communicated with the gas-liquid separator through a refrigerant connecting pipe, and the air exhaust port is communicated with the oil separator through the refrigerant connecting pipe. The low-temperature compressor can realize variable capacity adjustment of a low-temperature stage by changing the rotating speed of the compressor, so that the variable capacity adjustment of the whole heat pump system is realized, and the air supply temperature of the heat pump can be accurately controlled.

The evaporator is a refrigerant-water heat exchanger, and is provided with a refrigerant channel and a water channel, and the evaporator is commonly used in shell-and-tube heat exchangers, plate heat exchangers and the like. The water channel of the evaporator is communicated with the air recooling coil and the water pipe outlet through a water pipe.

The functions of the gas-liquid separator, the oil filter, the drying filter and the electronic expansion valve of the low-temperature circulation are similar to those of the same-name parts of the high-temperature circulation, and the description is omitted.

The working principle of the low-temperature cycle is that refrigerant in the evaporator absorbs heat from a water source and is gasified, then enters the gas-liquid separator, is subjected to gas-liquid separation and then enters the low-temperature compressor, and the refrigerant gas is compressed into high-temperature and high-pressure refrigerant gas. Then, the refrigerant enters an oil separator, and the lubricating oil in the oil separator returns to a suction port of the low-temperature compressor along an oil return pipe after passing through an oil filter; the refrigerant enters a condensing evaporator to be liquefied and release heat to the high-temperature circulating refrigerant. The refrigerant then flows back to the evaporator through a filter drier and an electronic expansion valve, completing the low temperature cycle of the refrigerant.

(III) air flow path

The air preheating coil is a water-air heat exchanger, and is provided with a water channel and an air channel, and the common type is a finned tube heat exchanger and the like. The water channel of the air preheating coil is communicated with the air precooling coil and the circulating water pump through a water pipe, and the air channel of the air preheating coil is communicated with the air inlet and the condenser through an air channel.

The air pre-cooling coil is a water-air heat exchanger, and is provided with a water channel and an air channel, and the common type is a finned tube heat exchanger and the like. The water channel of the air pre-cooling coil is communicated with the circulating water pump and the air pre-heating coil through a water pipe, and the air channel of the air pre-cooling coil is communicated with the condenser and the air pre-cooling coil through an air duct.

The air recooling coil is a water-air heat exchanger and is provided with a water channel and an air channel, and the air recooling coil is of a common type such as a finned tube heat exchanger. The water channel of the air recooling coil is communicated with the chilled water pump and the evaporator through a water pipe, and the air channel of the air recooling coil is communicated with the air precooling coil and the fan through an air channel.

The air inlet, the air preheating coil, the condenser, the air precooling coil, the air recooling coil, the fan and the air outlet are sequentially connected through an air duct to form an air flow path of the high-temperature heat pump experiment table.

The working principle of the air flow path is that inlet air firstly passes through the air preheating coil pipe, absorbs loop water heat to be preheated, is further heated to a specified temperature through the condenser, then passes through the air precooling coil pipe, releases heat to the loop water, is precooled, finally passes through the air recooling coil pipe, releases heat to chilled water, is further cooled to below 40 ℃, and is discharged to the environment through the fan, so that potential safety hazards do not exist to people or objects near the air outlet.

(IV) chilled water (or cooling water) flow path

The refrigerated water inlet, the refrigerated water pump, the air recooling coil pipe, the evaporator and the refrigerated water outlet are sequentially connected through the refrigerated water pipe to form a refrigerated water flow path of the high-temperature heat pump experiment table.

The working principle of the chilled water flow path is that inlet chilled water firstly enters air through a chilled water pump and then enters the air recooling coil, absorbs air heat to cool the air, then enters the evaporator, releases heat to the refrigerant, and finally is discharged from a chilled water outlet. The chilled water is used as the heat source of the high-temperature heat pump experiment table, and compared with the method of directly absorbing heat from the environment, the temperature of the heat source is more stable, and the system control is simpler.

(V) Loop Water flow Path

The air preheating coil, the air precooling coil and the circulating water pump are sequentially connected end to end through a circulating water pipe to form a loop water flow path of the high-temperature heat pump experiment table. The loop water flow path is also provided with an expansion tank and a water replenishing port.

The working principle of the loop water flow path is that under the action of the loop water pump, loop water firstly enters the air precooling coil to absorb the heat of air, thereby having the precooling effect on the air, and then enters the air preheating coil to release heat to supply the air, thereby having the preheating effect on the air. The preheating and precooling before and after the condenser are realized by adopting the loop water, so that the load of the condenser can be reduced, and if the preheating is not carried out, the air supply temperature is difficult to be directly heated to more than 100 ℃ from the ambient temperature; on the other hand, the air return system can be avoided, so that the complexity of the air duct design is reduced.

Compared with the prior art, the invention has the following advantages:

1) the overlapping type high-temperature heat pump experiment table adopts a unique variable capacity adjusting method, not only can realize the variable capacity adjustment of a heat pump system by unloading a compressor at a high-temperature stage or closing the air injection enthalpy increasing function, but also can realize the variable capacity adjustment of the heat pump system by the frequency conversion at a low-temperature stage, thereby accurately controlling the heat supply temperature of a heat pump;

2) the air duct design without return air in the cascade high-temperature heat pump experiment table can realize heating at the temperature of more than 100 ℃ and also can ensure that exhaust air has no safety hazard to the surroundings;

3) according to the cascade high-temperature heat pump experiment table, through the design of the loop water and the air preheating and precooling coil pipes, the preheating and precooling of the air can be realized, the load of a condenser is reduced, and the high-temperature heating at the temperature of more than 100 ℃ is easier to realize;

4) according to the cascade high-temperature heat pump experiment table, the super-large supercooling degree can be generated for the system by arranging the cooler in front of the valve, and the temperature in front of the valve is obviously reduced on the premise of not losing the performance of the system, so that the expansion valve is ensured to operate in a safe range.

Drawings

Fig. 1 is a schematic diagram of the structure and the flow of a cascade high-temperature heat pump experiment table in embodiment 1.

In the figure:

1A and 1B are high temperature enhanced vapor injection compressors (a is an air suction port, B is an air supplement port, C is an exhaust port), 2 is a condenser, 3A and 3B are economizers, 4 is a pre-valve cooler, 5 is a condensing evaporator, 6 is a gas-liquid separator, 7 is an oil separator, 8 is a reservoir, 9 is an oil filter, 10 is a drying filter, 11 is an electronic expansion valve (EXV), 11A and 11B are economizers EXV, 11C is a pre-valve cooler EXV, 11D is a condensing evaporator EXV, 12A and 12B are solenoid valves, 13A and 13B are check valves, 14 is a low temperature compressor, 15 is an evaporator, 16 is a gas-liquid separator, 17 is an oil separator, 18 is an oil filter, 19 is a drying filter, 20 is an electronic expansion valve (EXV), 21 is an air inlet, 22 is an air pre-cooling coil, 23 is an air pre-cooling coil, 24 is an air re-cooling coil, 25 is a fan, 26 is an air outlet, 27 is a chilled water inlet, 28 is a chilled water pump, 29 is a chilled water outlet, 30 is a circulating water pump, 31 is an expansion tank, 32 is a water replenishing port, 33, 34, 35A, 35B, 36A, 36B, 37A, 37B, 38A, 38B, 39A, 39B, 40, 41, 42, 43A, 43B, 44A, 44B, 45A, 45B, 46, 47, 48, 49, 50A, 50B, 51A, 51B, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66 are refrigerant connecting pipes, 67, 68, 69A, 69B, 70, 71 are oil return pipes, 72, 73, 74, 75, 76, 77 are air ducts, 78, 79, 80, 81 are chilled water pipes, 82, 83, 84 are circulating water pipes.

Fig. 2 is a schematic diagram of the structure and the flow of the cascade high-temperature heat pump experiment table in embodiment 2.

In the figure:

1A and 1B are high temperature enhanced vapor injection compressors (a is an air suction port, B is an air supplement port, C is an exhaust port), 2 is a condenser, 3A and 3B are economizers, 4 is a pre-valve cooler, 5 is a condensing evaporator, 6 is a gas-liquid separator, 7 is an oil separator, 8 is a reservoir, 9 is an oil filter, 10 is a drying filter, 11 is an electronic expansion valve (EXV), 11A and 11B are economizers EXV, 11C is a pre-valve cooler EXV, 11D is a condensing evaporator EXV, 12A and 12B are solenoid valves, 13A and 13B are check valves, 14 is a low temperature compressor, 15 is an evaporator, 16 is a gas-liquid separator, 17 is an oil separator, 18 is an oil filter, 19 is a drying filter, 20 is an electronic expansion valve (EXV), 21 is an air inlet, 22 is an air pre-cooling coil, 23 is an air pre-cooling coil, 24 is an air re-cooling coil, 25 is a fan, 26 is an air outlet, 27 is a cooling water inlet, 28 is a cooling water pump, 29 is a cooling water outlet, 30 is a circulating water pump, 31 is an expansion tank, 32 is a water replenishing port, 33, 34, 35A, 35B, 36A, 36B, 37A, 37B, 38A, 38B, 39A, 39B, 40, 41, 42, 43A, 43B, 44A, 44B, 45A, 45B, 46, 47, 48, 49, 50A, 50B, 51A, 51B, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66 are refrigerant connecting pipes, 67, 68, 69A, 69B, 70, 71 are oil return pipes, 72, 73, 74, 75, 76, 77 are air ducts, 78, 79, 80, 81 are cooling water pipes, 82, 83, 84 are circulating water pipes.

Fig. 3 is a schematic diagram of the structure and the flow of the cascade high-temperature heat pump experiment table in embodiment 3.

In the figure:

1A and 1B are high temperature enhanced vapor injection compressors (a is an air suction port, B is an air supplement port, C is an exhaust port), 2 is a condenser, 3A and 3B are economizers, 4 is a pre-valve cooler, 5 is a condensing evaporator, 6 is a gas-liquid separator, 7 is an oil separator, 8 is a reservoir, 9 is an oil filter, 10 is a drying filter, 11 is an electronic expansion valve (EXV), 11A and 11B are economizers EXV, 11C is a pre-valve cooler EXV, 11D is a condensing evaporator EXV, 12A and 12B are solenoid valves, 13A and 13B are check valves, 14 is a low temperature compressor, 15 is an evaporator, 16 is a gas-liquid separator, 17 is an oil separator, 18 is an oil filter, 19 is a drying filter, 20 is an electronic expansion valve (EXV), 21 is an air inlet, 22 is an air pre-cooling coil, 23 is an air pre-cooling coil, 24 is an air re-cooling coil, 25 is a fan, 26 is an air outlet, 27 is a chilled water inlet, 28 is a chilled water pump, 29 is a chilled water outlet, 30 is a circulating water pump, 31 is an expansion tank, 32 is a water replenishing port, 33, 34, 35A, 35B, 36A, 36B, 37A, 37B, 38A, 38B, 39A, 39B, 40, 41, 42, 43A, 43B, 44A, 44B, 45A, 45B, 46, 47, 48, 49, 50A, 50B, 51A, 51B, 52, 53 and 54, 55. 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66 are refrigerant connecting pipes, 67, 68, 69A, 69B, 70, 71 are oil return pipes, 72, 73, 74, 75, 76, 77 are air ducts, 78, 79, 80, 81 are freezing water pipes, 82, 83, 84 are circulating water pipes, 85 is a heat supply end, 86, 87 are manual ball valves (or manual stop valves), 88, 89, 90, 91 are refrigerant connecting pipes.

Detailed Description

The invention is described in detail below with reference to the figures and specific embodiments.

Example 1

The structure and the flow of the cascade high-temperature heat pump experiment table in the embodiment are shown in fig. 1, and the main structure comprises a refrigerant flow path, an air flow path and a water flow path.

The refrigerant flow path includes a high temperature cycle and a low temperature cycle. The high-temperature cycle comprises high-temperature enhanced vapor injection compressors 1A and 1B (a is an air suction port, B is an air supplement port, and C is an exhaust port), a condenser 2, economizers 3A and 3B, a pre-valve cooler 4, a condensing evaporator 5, a gas-liquid separator 6, an oil separator 7, a liquid reservoir 8, an oil filter 9, a drying filter 10, electronic expansion valves 11A, 11B, 11C and 11D, electromagnetic valves 12A and 12B, check valves 13A and 13B, refrigerant connecting pipes 33, 34, 35A, 35B, 36A, 36B, 37A, 37B, 38A, 38B, 39A, 39B, 40, 41, 42, 43A, 43B, 44A, 44B, 45A, 45B, 46, 47, 48, 49, 50A, 50B, 51A, 51B, 52, 53, 54, 55, 56, 57 and 58, and oil return pipes 67, 68, 69A and 69B; the low-temperature cycle includes a low-temperature compressor 14, an evaporator 15, a condenser-evaporator 5, a gas-liquid separator 16, an oil separator 17, an oil filter 18, a dry filter 19, an electronic expansion valve 20, refrigerant connection pipes 59, 60, 61, 62, 63, 64, 65, 66, and oil return pipes 70, 71.

The air flow path includes air inlet 21, air preheat coil 22, condenser 2, air pre-cool coil 23, air re-cool coil 24, fan 25, air outlet 26, air stacks 72, 73, 74, 75, 76, 77.

The water flow path includes a chilled water flow path and a loop water flow path. Wherein, the chilled water flow path comprises a chilled water inlet 27, a chilled water pump 28, an air recooling coil 24, an evaporator 15, a chilled water outlet 29, and chilled water pipes 78, 79, 80, 81; the loop water flow path comprises an air preheating coil 22, an air precooling coil 23, a circulating water pump 30, an expansion tank 31, a water replenishing port 32 and circulating water pipes 82, 83 and 84.

High temperature cycle

The high-temperature compressors 1A and 1B are two parallel enhanced vapor injection compressors, and compared with the common compressor, the high-temperature compressors are provided with an air suction port a and an air exhaust port c, and an air supplement port B is added. Wherein, the suction port a is communicated with the gas-liquid separator 6 through refrigerant connecting pipes 34, 35A (B), 36A (B), the air supplementing port b is communicated with the economizer 3A (B) through a refrigerant connecting pipe 37A (B), and the exhaust port c is communicated with the check valve 13A (B) through a refrigerant connecting pipe 38A (B). If single-stage compression is adopted, the pressure ratio is large, the exhaust temperature is too high, and two-stage compression can be realized by using the enhanced vapor injection compressor, so that the exhaust temperature is obviously reduced, and the heating capacity of the heat pump system is improved. Meanwhile, two parallel air injection enthalpy-increasing compressors are adopted, and the variable capacity adjustment of the heat pump system can be realized by unloading one compressor or closing the air injection enthalpy-increasing function.

The condenser 2 is a refrigerant-air heat exchanger having refrigerant channels and air channels, and is of a common type such as a finned tube heat exchanger, a microchannel heat exchanger, or the like. The refrigerant channel of the condenser 2 is communicated with the oil separator 7 and the liquid accumulator 8 through refrigerant connecting pipes 40 and 41, and the air channel of the condenser 2 is communicated with the air preheating coil 22 and the air pre-cooling coil 23 through air pipes 73 and 74.

The economizers 3A and 3B are refrigerant-refrigerant heat exchangers provided with two refrigerant channels, common types such as plate heat exchangers and the like. Wherein, the high-temperature channel inlet of the economizer 3A (B) is communicated with the electromagnetic valve 12A (B) through a refrigerant connecting pipe 44A (B), and the high-temperature channel outlet is communicated with the pre-valve cooler 4 through refrigerant connecting pipes 45A (B), 46; the inlet of the low-temperature channel of the economizer 3a (b) is communicated with the electronic expansion valve 11a (b) through a refrigerant connecting pipe 51a (b), and the outlet of the low-temperature channel is communicated with the air supplement port b of the enhanced vapor injection compressor 1a (b) through a refrigerant connecting pipe 37a (b). The economizer 3A (B) can realize air supplement of an air supplement port of the compressor, and can further increase the supercooling degree and reduce the temperature before the valve.

The pre-valve cooler 4 is a refrigerant-refrigerant heat exchanger, and has two refrigerant channels, such as a plate heat exchanger. Wherein, the high-temperature channel inlet of the pre-valve cooler 4 is communicated with the economizer 3A (B) through refrigerant connecting pipes 45A (B) and 46, and the high-temperature channel outlet is communicated with the drying filter 10 through a refrigerant connecting pipe 47; the low-temperature passage inlet of the pre-valve cooler 4 is communicated with the electronic expansion valve 11C through a refrigerant connection pipe 54, and the low-temperature passage outlet is communicated with the gas-liquid separator 6 through refrigerant connection pipes 55, 33. The pre-valve cooler 4 can further increase the supercooling degree to reduce the pre-valve temperature to below 60 ℃, and meanwhile, the low-temperature refrigerant channel of the pre-valve cooler 4 and the refrigerant channel of the condensation evaporator 5 are in parallel connection, so that the flow of part of the refrigerant passing through the condensation evaporator 5 can be reduced, and the liquid separation of the refrigerant of the condensation evaporator 5 can be realized more easily.

The condensing evaporator 5 is a refrigerant-refrigerant heat exchanger, and has two refrigerant channels, such as a plate heat exchanger. Wherein, the inlet of the high temperature channel (condensation side) of the condensation evaporator 5 is communicated with the gas-liquid separator 17 through a refrigerant connecting pipe 63, and the outlet of the high temperature channel (condensation side) is communicated with the drying filter 19 through a refrigerant connecting pipe 64; the low-temperature passage (evaporation side) inlet of the pre-valve cooler 5 is communicated with the electronic expansion valve 11D through the refrigerant connection pipe 57, and the low-temperature passage outlet is communicated with the gas-liquid separator 6 through the refrigerant connection pipes 58, 33.

The gas-liquid separator 6 has the functions of realizing gas-liquid separation, preventing the gas absorption and liquid carrying of the compressor 1A and B, avoiding damage to power parts of the compressor and playing a role in protecting the compressor. Wherein, the inlet of the gas-liquid separator 6 is communicated with the pre-valve cooler 4 and the condensing evaporator 5 through refrigerant connecting pipes 33, 55, 58, and the outlet is communicated with the suction port a of the compressor 1A (B) through refrigerant connecting pipes 34, 35A (B), 36A (B).

The oil separator 7 is used for separating lubricating oil in high-pressure steam discharged by the compressor 1A (B) so as to ensure the safe and efficient operation of the unit. Wherein, the inlet of the oil separator 7 is communicated with the one-way valve 13a (b) through a refrigerant connecting pipe 39a (b), the refrigerant outlet is communicated with the condenser 2 through a refrigerant connecting pipe 40, and the oil outlet is communicated with the oil filter 9 through an oil return pipe 67.

The reservoir 8, functions to accommodate the change in charge at varying system loads. Wherein the inlet of the accumulator 8 is communicated with the condenser 2 through a refrigerant connection pipe 41, and the outlet is communicated with the solenoid valve 12a (b) through a refrigerant connection pipe 42, 43a (b).

The oil filter 9, which functions to filter the oil, keeps the oil flowing back to the compressor clean. Wherein, the inlet of the oil filter 9 is communicated with the oil separator 7 through an oil return pipe 67, and the outlet is communicated with the suction port a of the compressor 1A (B) through oil return pipes 68, 69A (B) and a refrigerant connecting pipe 36A (B).

The filter drier 10 is used for filtering impurities in the refrigerant to prevent the impurities from entering the electronic expansion valve and blocking the electronic expansion valve. Wherein, the inlet of the dry filter 10 is communicated with the pre-valve cooler 4 through a refrigerant connection pipe 47, and the outlet is communicated with the electronic expansion valve 11A (B/C/D) through refrigerant connection pipes 48, 49, 50a (B), 52, 53, 56.

The electronic expansion valve 11A has the function of adjusting the refrigerant flow of the economizer 3A by controlling the superheat degree of the refrigerant at the outlet of the low-temperature passage of the economizer 3A; the electronic expansion valve 11B has the function of adjusting the refrigerant flow of the economizer 3B by controlling the superheat degree of the refrigerant at the outlet of the low-temperature channel of the economizer 3B; an electronic expansion valve 11C, which functions to adjust the refrigerant flow of the front cooler 4 by controlling the superheat degree of the refrigerant at the outlet of the low-temperature channel of the front cooler 4; and the electronic expansion valve 11D has the function of adjusting the refrigerant flow of the condensation evaporator 5 by controlling the superheat degree of the refrigerant at the outlet of the low-temperature channel of the condensation evaporator 5.

Solenoid valves

12A and 12B function to unload or shut down the enhanced vapor injection function of any compressor for a single compressor. Wherein the inlet of the solenoid valve 12a (b) is communicated with the accumulator 8 through a refrigerant connecting pipe 42, 43a (b), and the outlet is communicated with the economizer 3a (b) through a refrigerant connecting pipe 44a (b).

The check valves 13A and 13B function to prevent the refrigerant from flowing back to the compressor after the shutdown. Wherein, the inlet of the check valve 13a (b) is communicated with the exhaust port c of the high-temperature compressor 1a (b) through a refrigerant connecting pipe 38a (b), and the outlet is communicated with the oil separator 7 through a refrigerant connecting pipe 39a (b).

The working principle of the high-temperature cycle is that after the refrigerant in the condensing evaporator 5 absorbs heat from a low-temperature stage and is gasified, the refrigerant is mixed with the low-temperature refrigerant gasified in the pre-valve cooler 4 and enters the gas-liquid separator 6, after gas-liquid separation, the refrigerant is divided into two paths and respectively enters the air suction ports a of the enhanced vapor injection compressors 1A and 1B, and when the refrigerant gas is compressed to an intermediate state, the refrigerant gas is mixed with the refrigerant gas entering the air supplement port B and is compressed for the second time to become the high-temperature high-pressure refrigerant gas. Then, the two paths of refrigerants both enter the oil separator 7 after passing through the one-way valve 13A (B), and lubricating oil in the two paths of refrigerants passes through the oil filter 9 and returns to the air suction port a of the compressor 1A (B) along an oil return pipe; the refrigerant enters the condenser 2 to heat the air. Then, the refrigerant is divided into two paths after passing through the liquid storage device 8, one path of the refrigerant flows through the electromagnetic valve 12A and enters the economizer 3A, the other path of the refrigerant flows through the electromagnetic valve 12B and enters the economizer 3B, the two paths of the refrigerant are respectively cooled by the refrigerant in the low-temperature channel, then the refrigerant is merged and enters the pre-valve cooler 4, and the refrigerant is further cooled to below 60 ℃ (the temperature is lower than the tolerance temperature of a conventional electronic expansion valve). Then, the refrigerant is divided into four paths by a drying filter 10, one path of refrigerant enters the economizer 3A through an electronic expansion valve 11A, and is gasified into refrigerant gas and then enters an air supplement port b of the compressor 1A; one path of refrigerant enters the economizer 3B through the electronic expansion valve 11B, is gasified into refrigerant gas and then enters an air supplement port B of the compressor 1B; one path of refrigerant enters the pre-valve cooler 4 through the electronic expansion valve 11C to be gasified into refrigerant gas and then enters the gas-liquid separator 6; the other path of refrigerant enters the condensation evaporator 5 through the electronic expansion valve 11D and is gasified into refrigerant gas, and then enters the gas-liquid separator 6 to complete the high-temperature circulation of the whole refrigerant.

(II) Low temperature circulation

The low-temperature compressor 14 is an inverter compressor and has an intake port and an exhaust port. The suction port is communicated with the gas-liquid separator 16 through refrigerant connection pipes 61 and 60, and the discharge port is communicated with the oil separator 17 through a refrigerant connection pipe 62. The low-temperature compressor 14 can realize variable capacity adjustment of a low-temperature stage by changing the rotating speed of the compressor, so that the variable capacity adjustment of the whole heat pump system is realized, and the air supply temperature of the heat pump can be accurately controlled.

The evaporator 15 is a refrigerant-water heat exchanger having a refrigerant passage and a water passage, and is typically a shell-and-tube heat exchanger, a plate heat exchanger, or the like. Wherein the refrigerant passageway of the evaporator 15 is in communication with the electronic expansion valve 20 and the vapor-liquid separator 16 via refrigerant connection tubes 66, 59, and the water passageway of the evaporator 15 is in communication with the air sub-cooling coil 24 and the water tube outlet 29 via water tubes 80, 81.

The gas-liquid separator 16 has the functions of realizing gas-liquid separation, preventing the compressor 14 from sucking gas and carrying liquid, avoiding damage to power parts of the compressor and protecting the compressor. Wherein, the inlet of the gas-liquid separator 16 is communicated with the evaporator 15 through a refrigerant connecting pipe 59, and the outlet is communicated with the suction port of the compressor 14 through refrigerant connecting pipes 60, 61.

The oil separator 17 is used for separating lubricating oil in high-pressure steam discharged from the compressor 14, so as to ensure that the unit can safely and efficiently operate. Wherein, the inlet of the oil separator 17 is communicated with the compressor 14 through a refrigerant connecting pipe 62, the refrigerant outlet is communicated with the condensing evaporator 5 through a refrigerant connecting pipe 63, and the oil outlet is communicated with the oil filter 18 through an oil return pipe 70.

The oil filter 18, functions to filter the oil and keep the oil flowing back to the compressor clean. Wherein, the inlet of the oil filter 18 is communicated with the oil separator 17 through an oil return pipe 70, and the outlet is communicated with the suction port of the compressor 14 through an oil return pipe 71 and a refrigerant connecting pipe 61.

The dry filter 19 is used for filtering impurities in the refrigerant, and preventing the impurities from entering the electronic expansion valve and being blocked. Wherein the inlet of the dry filter 19 is communicated with the condensing evaporator 5 through a refrigerant connection pipe 64, and the outlet is communicated with the electronic expansion valve 20 through a refrigerant connection pipe 65.

The electronic expansion valve 20 functions to adjust the refrigerant flow rate of the evaporator 15 by controlling the degree of superheat at the refrigerant outlet of the evaporator 15.

The low-temperature cycle operates on the principle that the refrigerant in the evaporator 15 absorbs heat from a water source and is gasified, then enters the gas-liquid separator 16, is subjected to gas-liquid separation, and then enters the low-temperature compressor 14, and is compressed into high-temperature and high-pressure refrigerant gas. The refrigerant then enters the oil separator 17, where the lubricating oil passes through the oil filter 18 and returns to the suction port of the low temperature compressor 14 along the oil return line; the refrigerant enters the condensing evaporator 5 to be liquefied and release heat to the high-temperature circulating refrigerant. Thereafter, the refrigerant flows back to the evaporator 15 through the dry filter 19 and the electronic expansion valve 20, completing the low temperature cycle of the refrigerant.

(III) air flow path

The air preheating coil 22 is a water-air heat exchanger having water and air passages, of the type commonly found in fin tube heat exchangers and the like. Wherein the water passage of the air preheating coil 22 is communicated with the air pre-cooling coil 23 and the circulating water pump 30 through water pipes 82 and 83, and the air passage of the air preheating coil 22 is communicated with the air inlet 21 and the condenser 2 through air ducts 72 and 73.

Air pre-cooling coil 23 is a water-air heat exchanger having a water channel and an air channel, and is typically of the type such as a finned tube heat exchanger. The water passage of air pre-cooling coil 23 is in communication with circulating water pump 30 and air pre-heating coil 22 via water lines 84, 82, and the air passage of air pre-cooling coil 23 is in communication with condenser 2 and air sub-cooling coil 24 via air ducts 74, 75.

The air sub-cooling coil 24 is a water-air heat exchanger having water and air passages, of the type commonly found in fin tube heat exchangers and the like. The water path of air sub-cooling coil 24 is in communication with chilled water pump 28 and evaporator 15 via water lines 79 and 80, and the air path of air sub-cooling coil 24 is in communication with air pre-cooling coil 23 and fan 25 via air paths 75 and 76.

An air inlet 21, an air preheating coil 22, a condenser 2, an air pre-cooling coil 23, an air re-cooling coil 24, a fan 25 and an air outlet 26 are sequentially connected through air ducts 72, 73, 74, 75, 76 and 77 to form an air flow path of the high-temperature heat pump experiment table.

The working principle of the air flow path is that inlet air firstly passes through the air preheating coil 22, absorbs heat of loop water and is preheated, then is further heated to a specified temperature through the condenser 2, then passes through the air precooling coil 23, releases heat to the loop water, is precooled, finally passes through the air recooling coil 24, releases heat to chilled water, and is further cooled to below 40 ℃ and is discharged to the environment through the fan, so that potential safety hazards do not exist for people or objects near an air outlet.

(IV) chilled water flow path

The chilled water inlet 27, the chilled water pump 28, the air re-cooling coil 24, the evaporator 15 and the chilled water outlet 29 are sequentially connected through the chilled water pipes 78, 79, 80 and 81 to form a chilled water flow path of the high-temperature heat pump experiment table.

The working principle of the chilled water flow path is that inlet chilled water firstly enters the air recooling coil 24 through the chilled water pump 28, absorbs air heat to cool the air, then enters the evaporator 15, releases heat to the refrigerant, and finally is discharged from the chilled water outlet 29. The chilled water is used as the heat source of the high-temperature heat pump experiment table, and compared with the method of directly absorbing heat from the environment, the temperature of the heat source is more stable, and the system control is simpler.

(V) Loop Water flow Path

The air preheating coil 22, the air precooling coil 23 and the circulating water pump 30 are sequentially connected end to end through circulating water pipes 82, 83 and 84 to form a loop water flow path of the high-temperature heat pump experiment table. The loop water flow path is also provided with an expansion tank 31 and a water replenishing port 32.

The working principle of the loop water flow path is that under the action of the loop water pump 30, loop water firstly enters the air pre-cooling coil 23 to absorb the heat of air, so that the air is pre-cooled, and then enters the air pre-heating coil 22 to release heat to supply air, so that the air is pre-heated. The preheating and precooling before and after the condenser 2 are realized by adopting the loop water, so that the load of the condenser 2 can be reduced, and if the preheating is not carried out, the air supply temperature is difficult to be directly heated to more than 100 ℃ from the ambient temperature; on the other hand, the air return system can be avoided, so that the complexity of the air duct design is reduced.

Example 2

A cascade high-temperature heat pump experiment table is structurally and structurally shown in figure 2, and mainly structurally comprises a refrigerant flow path, an air flow path and a water flow path.

Compared with the embodiment 1, the heat source of the high-temperature heat pump experiment table is changed from chilled water (7 ℃) to cooling water (15-30 ℃), the flow direction of the cooling water is also changed, and the cooling water inlet 27, the cooling water pump 28, the evaporator 15, the air recooling coil 24 and the cooling water outlet 29 are sequentially connected through the cooling water pipes 78, 79, 80 and 81 to form a cooling water flow path of the high-temperature heat pump experiment table. Compare 7 ℃ of refrigerated water, cooling water temperature is higher relatively, consequently, the cooling water of import is through evaporimeter 15 cooling earlier, through air recooling coil 24 again, helps the cooling to the air, makes the temperature of airing exhaust as low as possible.

Example 3

The structure and the flow of the cascade high-temperature heat pump experiment table are shown in fig. 3, and the main structure comprises a refrigerant flow path, an air flow path and a water flow path.

Compared with the embodiment 1, only the heat supply terminal 85, the manual ball valves 86 and 87 and the refrigerant connection pipes 88, 89, 90 and 91 are added.

Compared with the embodiment 1, a part of the refrigerant at the outlet of the oil separator 7 flows through the condenser 2 through the refrigerant connecting pipe for heating the air; another portion of the refrigerant flows through the heating terminal 85 via refrigerant connecting pipes 88, 89 and manual ball valve 86, and may provide a heat source for other systems (e.g., ORC system) and returns to the front of the filter-drier 10 via refrigerant connecting pipes 90, 91 and manual ball valve 87. Manual ball valves 86, 87 can control the flow to the heating terminals and regulate the flow of refrigerant through the heating terminals.

The invention has the following advantages as can be seen from the examples: 1. adopting cascade circulation, wherein two parallel enhanced vapor injection compressors are adopted on the high-temperature side, and one variable-frequency compressor is adopted on the low-temperature side; 2. the design of an air duct without return air is adopted, the air preheating coil and the condenser realize high-temperature heating capacity, and the air precooling coil and the air recooling coil ensure that exhaust air has no safety hazard to the surroundings; 3. an air preheating coil and an air precooling coil are respectively arranged in front of and behind the condenser, so that the preheating and precooling of air can be realized; 4. the design that the cooler is connected with the condensing evaporator in parallel before the valve is adopted, the supercooling degree of the system can be increased, and the temperature before the valve is ensured to be lower than 60 ℃.

In the above embodiments, all the components of the refrigerant cycle are not completely shown, and in the implementation process, the refrigerant circuit is provided with common refrigeration accessories such as a liquid receiver, a filter, a dryer, and the like, which cannot be regarded as a substantial improvement of the present invention, and shall fall within the protection scope of the present invention.

The particular embodiments set forth above are not intended to be limiting and it will be apparent to those skilled in the art that various modifications and variations can be made without departing from the scope of the invention.

Claims

1. A cascade high-temperature heat pump experiment table is characterized by comprising a high-temperature circulation, a low-temperature circulation, an air flow path, a chilled water flow path and a loop water flow path;

the air flow path exchanges heat with high-temperature circulation through a condenser, exchanges heat with the upstream position of the chilled water flow path through an air re-cooling coil (24), and finally discharges the heat-exchanged air;

an air preheating coil (22) and an air precooling coil (23) are respectively arranged on the upstream side and the downstream side of the condenser;

the low-temperature circulation exchanges heat with a downstream position of the heat exchange chilled water flow path through the evaporator (15);

the low-temperature circulation exchanges heat with the high-temperature circulation through a condensing evaporator (5);

the loop water flow path is respectively connected into the air pre-cooling coil (23) and the air pre-heating coil (22) and exchanges heat with the air flow path.

2. The cascade high-temperature heat pump experiment table according to claim 1, wherein the high-temperature cycle comprises two enhanced vapor injection compressors, a condenser, an economizer assembly, a gas-liquid separator (6) and a liquid accumulator (8) which are connected in parallel;

the refrigerant absorbs heat from low-temperature circulation through a condensation evaporator (5) and is gasified, then is mixed with the refrigerant gasified in a cooler (4) in front of a valve, and enters a gas-liquid separator (6), after gas-liquid separation, the refrigerant is divided into two paths to respectively enter air suction ports of two enhanced vapor injection compressors, the refrigerant gas is compressed to an intermediate state, then is mixed with the refrigerant gas entering from air supply ports of the two enhanced vapor injection compressors, is compressed for the second time, is changed into high-temperature and high-pressure refrigerant gas, is respectively discharged from air discharge ports of the two enhanced vapor injection compressors, enters a condenser to heat an air flow path, then enters an economizer assembly after passing through a liquid storage device (8), and then flows back to the gas-liquid separator (6) and the air supply ports of the two enhanced vapor injection compressors through the economizer assembly to form high-temperature circulation.

3. The cascade high-temperature heat pump laboratory bench according to claim 2, characterized in that, the high-temperature cycle further comprises an oil separator (7) and an oil filter (9);

the oil separator (7) is arranged between the exhaust port of the enhanced vapor injection compressor and the condenser, the high-temperature and high-pressure refrigerant discharged from the exhaust port of the enhanced vapor injection compressor is separated by the oil separator (7), and the separated lubricating oil flows back to the air suction ports of the two enhanced vapor injection compressors respectively after passing through the oil filter (9); the separated refrigerant flows into a condenser.

4. A cascade high temperature heat pump laboratory bench according to claim 3, characterized in that said economizer module comprises two economizers and a pre-valve cooler (4);

refrigerant flows into the two economizers from the liquid storage device (8) respectively and is cooled by low-temperature channels in the two economizers respectively, then the refrigerant is merged and flows into the cooler (4) before the valve, so that the refrigerant is cooled to be below 60 ℃, and then the refrigerant flows back to the gas-liquid separator (6) and the air supplementing ports of the two enhanced vapor injection compressors through 4 flow paths;

the third flow path flows into a condensing evaporator (5) to exchange heat with low-temperature circulation;

the fourth flow path flows into the pre-valve cooler (4) and flows back to the gas-liquid separator (6);

an electronic expansion valve is arranged on a pipeline of the third flow path before flowing into the condensation evaporator (5);

the fourth flow path is provided with a valve front cooler (4) on a pipeline flowing into the gas-liquid separator (6);

two branch flow paths between the liquid storage device (8) and the two economizers are respectively provided with an electromagnetic valve, and the unloading of a single compressor or the closing of the enhanced vapor injection function of any compressor is realized through the closing of the electromagnetic valves.

5. The cascade high-temperature heat pump experiment table according to claim 1, wherein the low-temperature cycle comprises an oil separator, a dry filter (19), an electronic expansion valve (20), a gas-liquid separator and a low-temperature compressor (14) which are connected in sequence;

the low-temperature compressor (14) is connected with the oil separator to form a low-temperature cycle.

6. The cascade high temperature heat pump laboratory bench according to claim 5, characterized in that, the low temperature compressor (14) is a variable frequency compressor;

the low-temperature compressor (14) can realize variable capacity adjustment of a low-temperature stage by changing the rotating speed of the compressor, so that the variable capacity adjustment of the whole heat pump system is realized, and the air supply temperature of the heat pump can be accurately controlled.

7. The cascade high-temperature heat pump experiment table according to claim 1, wherein the air flow path comprises an air duct, one end of the air duct is provided with an air inlet (21), the other end of the air duct is provided with an air outlet (26), and the air duct is internally provided with an air preheating coil (22), a condenser, an air precooling coil (23), an air recooling coil (24) and a fan (25) in sequence from the air inlet (21) end to the air outlet (26) end.

8. The cascade high-temperature heat pump laboratory bench according to claim 1, characterized in that, the chilled water flow path comprises a chilled water pipe, a chilled water pump (28) is arranged between a chilled water inlet (27) and a chilled water outlet (29);

the chilled water is pumped into the air re-cooling coil (24) by the chilled water pump (28) to exchange heat with the air flow path, and then flows into the evaporator (15) to exchange heat with low-temperature circulation.

9. The cascade high temperature heat pump test bench of claim 1, wherein said chilled water flow path is replaceable by a cooling water flow path, said cooling water flow path flowing in a direction opposite to the chilled water flow path, said cooling water temperature at the inlet being 15-30 ℃.

10. The compound high temperature heat pump bench of claim 4, wherein said compound high temperature heat pump bench further comprises a heat supply tip (85);

the inlet of the heat supply tail end (85) is connected with the outlet of the oil separator (7);

the outlet of the heat supply terminal (85) is connected with the first flow path, the second flow path, the third flow path and the fourth flow path.