JPS6256430B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a heat pump device that performs at least heating by driving a compressor using a heat engine powered by combustion energy such as city gas or kerosene. It is.

[Prior art]

BACKGROUND ART In recent years, from the viewpoint of energy conservation, there has been active development of cooling devices that perform heating and cooling using heat pumps that use combustion energy such as city gas or kerosene. This heat pump uses combustion energy to operate the engine, etc., which drives the heat pump compressor to perform heating and cooling.The exhaust heat of the engine during heating can be used for heating, so it is more efficient than electric heat pumps. It is energy saving. Therefore, it can also be used as a heating-only machine in cold regions.

[Problem that the invention seeks to solve]

However, this heat pump has major drawbacks as described below.

Normal capacity control includes compressor capacity control (turbo compressor vane control, screw compressor slide valve control, reciprocating compressor number control, etc.), heat engine rotation speed control, or a combination of these. Control is being carried out, but there is a lower limit (20 to 50%) in the controllable capacity range, and capacity control that corresponds to loads below this limit has not been possible.

SUMMARY OF THE INVENTION An object of the present invention is to provide a heat pump device that solves the problems of the conventional heat pump and enables capacity control for small loads that cannot be handled by normal capacity control.

[Means for solving problems]

The present invention provides a heat pump consisting of a compressor driven by a heat engine, an outside air side heat exchanger, a load side heat exchanger, an expansion device, and a refrigerant path connecting these devices, and a heat pump that detects the load and controls the capacity. In a heat pump device having a capacity control device, the refrigerant path includes an auxiliary evaporator arranged in parallel with the outside air side heat exchanger, a load fluid path leading a load fluid path to the load side heat exchanger, and the auxiliary evaporator. An auxiliary heat source path that guides the load fluid to the evaporator, a load detection device that detects the load, and compares the obtained detected value with the set value,
and a flow rate ratio control device that controls a refrigerant flow rate ratio to the outside heat exchanger and the auxiliary evaporator based on the detected value when the load falls below a lower limit of a predetermined controllable range. This heat pump device is characterized by:

〔Example〕

The present invention will be explained with reference to the drawings based on examples.

In the heat pump device for cooling and cooling shown in the drawing, 1 is a compressor, 3 is an outside air side heat exchanger, 7 is a load side heat exchanger, 9 is an expansion valve as an expansion device, and each device is connected by a refrigerant path. A heat pump is formed. The heat pump is equipped with a capacity control device that detects the load and controls the capacity. Note that a four-way valve 2, an expansion valve 6, and check valves 4 and 8 are provided in the refrigerant path to enable switching to cooling operation. 5 is a receiver.

The heat pump is further provided with an auxiliary evaporator 23 in parallel with the outside air side heat exchanger 3. In this embodiment, the refrigerant path connecting the refrigerant path between the receiver 5 and the expansion valve 9 and the outside air side heat exchanger 3 and the four-way valve 2 is a bypass bypass that bypasses the outside air side heat exchanger 3. Deployed as a branch route 37,
A bypass valve 21 and an expansion valve 2 are provided in the bypass path 37.
2 and an auxiliary evaporator 23 are provided.

Reference numeral 25 denotes an engine used as a heat engine for driving the compressor 1. For example, a jacket 1 is used as an exhaust heat recovery device for recovering exhaust heat from the engine 25.
1 is equipped with an exhaust gas heat exchanger 14.

A load fluid path that bypasses the load side heat exchanger 7 is branched into a load fluid path that leads the load fluid to the load side heat exchanger 7 as a bypass path 19 . The bypass path 19 connects the jacket 11 of the engine 25, the coolant cooler 10, and the exhaust gas heat exchanger 1.
4, an auxiliary heat source path 16 that bypasses the coolant cooler 10 and passes through the auxiliary evaporator 23 is branched. 12
is a pump, 13 is a three-way valve, 15, 17, 18 are three-way switching valves, and 20 is a solenoid valve.

The heat pump device formed as described above further includes a load detection device that detects the load, and compares the obtained detected value with a set value, and when the load falls below the lower limit of a predetermined controllable range, Based on the detected value, the outside air side heat exchanger 3 and the auxiliary evaporator 23
A flow rate ratio control device is provided to control the refrigerant flow rate ratio to and. The load detection device may be used as long as it detects the load, that is, the amount of load, and the inlet temperature and outlet temperature of the load fluid (hot water) (temperature detector 3
2) Alternatively, a detection device such as a temperature difference between entrance and exit is used. The flow rate ratio control device includes a control mechanism 35 and a bypass valve 21, and the control mechanism 35 compares the detected value obtained by the load detection device with a set value, and determines that the load has fallen below the lower limit of a predetermined controllable range. Sometimes, the flow rate ratio is controlled based on the detected value. That is, the signal from the detection device is compared with a predetermined setting value, and a signal corresponding to the input signal is output according to feedback or according to a predetermined program, and with this output signal,
The bypass valve 21 is controlled to have a predetermined flow rate ratio.

Therefore, the normal heat pump cycle is similar to that of a general electric air source heat pump.
In other words, during summer cooling, the refrigerant flows through the compressor 1 → four-way valve 2 → outside air side heat exchanger 3 (operates as a condenser)
→ Check valve 4 → Receiver 5 → Expansion valve 6 → Load side heat exchanger 7 (operates as an evaporator) → Four-way valve 2 →
The cold water is circulated in the order of the compressor 1 and cooled in the load side heat exchanger 7.

During heating, the four-way valve 2 is switched to change the path of the refrigerant, compressor 1 → four-way valve 2 → load side heat exchanger 7 (acts as a condenser) → check valve 8 → receiver 5 → expansion valve 9 → outside air side The hot water is circulated in the order of heat exchanger 3 (acting as an evaporator) → four-way valve 2 → compressor 1, and the hot water is heated in the load-side heat exchanger 7.

The normal capacity control of the heat pump during cooling or normal heating (medium to large capacity control range) is performed by the capacity control device built into the compressor 1, for example, in the case of a multi-cylinder reciprocating compressor, the number of cylinders is controlled. A vane control device is used for a turbo compressor, a slide valve control device is used for a screw compressor, etc. Further, even if the compressor 1 does not include a capacity control device, the capacity can be adjusted by changing the rotation speed of the heat engine. As described above, any type of compressor with any type of structure may be used as a heat pump compressor, regardless of the presence or absence of a capacity control device.

On the other hand, the cycle on the engine 25 side is as follows. During cooling, the exhaust heat from the jacket 11 is cooled by the outside air by the cooling medium cooler 10.
That is, the coolant that has been heated by cooling the jacket 11 is sucked in by the pump 12, sent to the coolant cooler 10, and cooled there. The water is then supplied to the jacket 11 again via the three-way valve 13.

During heating, the three-way switching valves 15, 17, and 18 are switched, and the solenoid valve 20 is opened so that the exhaust heat from the engine 25 is used to heat the hot water. That is, the cooling water heated by cooling the jacket 11 (that is, a portion of the hot water that is the load fluid) is sucked in by the pump 12, passes through the three-way switching valve 15, the auxiliary heat source path 16, and the auxiliary evaporator 23. Thereafter, it is sent to the exhaust gas heat exchanger 14 via the three-way switching valve 17 and further heated by the exhaust gas.

The heated hot water joins the hot water from the load-side heat exchanger 7 via the three-way switching valve 18, and is used for heating the load. Solenoid valve 2 handles hot water when the load temperature drops.
0, and the jacket 11 is cooled again. Note that when the load is light, the temperature of the hot water supplied to the jacket 11 may be too high, so the supplied temperature is detected by the temperature detector 24 and regulated by the three-way valve 13 so that the temperature is approximately constant.

Since the heating load is usually smaller than the cooling load, the rotational speed of the engine 25 may be set lower during heating than during cooling.

Among the above parallel refrigerant paths, outside air side heat exchanger 3
The path including the outside air heating path is referred to as the outside air heating path, and the path including the auxiliary evaporator 23 is referred to as the heat engine heating path. In the illustrated embodiment, the auxiliary evaporator 23 indirectly uses the exhaust heat of the engine 25 to heat the refrigerant, but it also uses hot water whose temperature has been raised by the output of the heat engine. You can also heat it by
Since the exhaust heat from the heat engine is used directly or indirectly to heat the refrigerant, it will be referred to as a heat engine-based heating path.

In the heat pump device configured as above,
First, for reference, capacity control in response to changes in outside temperature will be explained.

During heating, when the outside temperature is sufficiently high, the bypass valve 21 is closed, the entire amount of refrigerant is guided to the outside air heating path, and the heat source of the heat pump is taken only from the outside air.

If the outside temperature drops to a certain extent, the heating capacity will drop, so the load is detected based on the temperature of the load fluid, and the rotation speed of the engine 25 is automatically controlled and increased based on the detected value. As described above, even in a device in which the rotational speed during heating is set lower than the rotational speed during cooling, the capacity may be increased by increasing the set number of rotations.

Further, the capacity control mechanism and rotation speed control of the compressor 1 may be used together to increase the capacity. These methods can be operated in reverse if capacity needs to be reduced.

If the outside temperature further decreases, no matter how much you try to increase the amount of refrigerant gas sucked into the compressor 1, the inlet pressure of the compressor 1 will decrease and the specific volume of the refrigerant gas will increase, so a sufficient refrigerant flow rate will be ensured. In addition, as the temperature decreases, frost appears on the outside air side heat exchanger 3, which further impedes the supply of heat from the heat source and reduces the heating capacity. In order to prevent
The opening degree of the bypass valve 21 is appropriately selected and opened, and the flow rate ratio of the refrigerant flow rate guided to the outside air heating path and the heat engine heating path is controlled by the opening degree of the bypass valve 21. That is,
Heat is introduced into the refrigerant from the auxiliary evaporator 23 in proportion to the amount of heat that cannot be obtained from the outside air side heat exchanger 3, and the refrigerant evaporated in both the outside air side heat exchanger 3 and the auxiliary evaporator 23 is transferred to the compressor. Let it be absorbed into 1.

In this way, the evaporation pressure increases by the amount that the burden capacity of the outside air side heat exchanger 3 is reduced, and if the heat transfer area is determined so that the auxiliary evaporator 23 also has sufficient capacity, the outside air side heat exchanger 3 and The pressure of the combined refrigerant from the auxiliary evaporator 23 increases, and the compressor 1 can suck in an extra flow rate of refrigerant than in a state where the pressure is low, thereby securing the amount of heat in the load-side heat exchanger 7. Can be done. The auxiliary evaporator 23 uses the exhaust heat of the engine 25 directly or indirectly. Although the drawing shows a cycle in which the heat of the hot water in the jacket 11 is directly used, the heat of the exhaust gas or the hot water in the load-side heat exchanger 7 may be used instead.

In this way, even when the outside temperature is abnormally low, the amount of heat taken in by the outside air side heat exchanger 3 can be reduced without reducing the heating capacity, and the operation can be operated with frost formation suppressed or eliminated. can be used to heat water by increasing the engine's capacity and incorporating its combustion energy into a heat pump system.

If the outside air temperature falls further abnormally, the bypass valve 21 will be fully opened and most of the load will be borne by the auxiliary evaporator 23. An on-off valve may also be provided in the outside air heating path, or a three-way valve may be provided at the branch point of the heat engine heating path and the outside air heating path for distribution adjustment.

An example of the control method will be explained. Although various control methods are shown in the drawings, this does not mean that they are all provided at the same time or that they all operate at the same time.They are drawn on the same drawing for convenience, and each control method may be used alone or in combination as appropriate. It is the type of equipment that is deployed or used.

Control that adapts the heating capacity according to the load, which is within the range of normal capacity control of the heat pump, uses, for example, a temperature detector 26 for the hot water temperature in the return path as a load detector, and uses its signal to adjust the capacity of the compressor 1. The return hot water temperature is kept approximately constant by using a control device or a combination of the rotation speed of the engine 25 and the capacity control device of the compressor 1.

Control of the load ratio between the outside air heating path and the heat engine heating path, that is, the flow rate ratio control of the bypass valve 21, is performed, for example, in the following manner.

As a detection end, the outside temperature (temperature detector 2
7) A detector for a physical quantity related to outside air temperature, such as evaporation pressure (pressure detector 28) or evaporation temperature (temperature detector 30), is selected, and a signal from one of them indicates that the evaporation pressure or evaporation temperature is approximately The flow rate of the bypass valve 21 is controlled so that the flow rate is constant.

Alternatively, as another control method, control may be performed using a preset program. For example, the outside air temperature (temperature detector 27) can be programmed with the opening degree of the bypass valve 21, the evaporation pressure (pressure detector 27)
8) and the opening degree of the bypass valve 21, the load (directly or indirectly detected by the temperature sensor 32, the engine speed sensor or the cooling water temperature sensor 31) and the outside air temperature (the temperature sensor 27) A program between the signal combination and the opening degree of the bypass valve 21 (using the control mechanism 33 or 34),
Combination of signals of load (temperature detector 32, engine speed detector or cooling water temperature detector 31) and evaporation pressure (pressure detector 29) and bypass valve 2
This is control by a program (using the control mechanism 35) between the opening degree of 1 and the opening degree.

Alternatively, as another control method, the temperature difference between the outside air temperature (temperature detector 27) and the evaporation temperature (temperature detector 30) is detected, and the bypass valve 21 is activated by the control mechanism 36.
The opening degree may be controlled by a program or so that the evaporation temperature or evaporation pressure is constant. This method is more preferable than other methods.

The various detection ends described above (temperature detector 27,
30, pressure detectors 28, 29) detect physical quantities related to outside air temperature,
In addition, for example, the suction pressure of the compressor 1 (approximately the same as the evaporation pressure) may be detected.

In addition to the above-mentioned heating source, the auxiliary evaporator 23 may use direct exhaust heat, or may use the load-side heat exchanger 7.
It may be heated by hot water at the inlet or outlet of the condenser.

In the above example, the capacity control device of the compressor 1 is used as load control in response to a drop in outside temperature, but the load ratio of the parallel refrigerant paths may be controlled without using this. Furthermore, even if the compressor 1 is equipped with a capacity control device, the capacity of the heat pump can be controlled by separately changing the rotation speed of the heat engine. Control can also be performed in combination with a control device.
Further, the compressor 1 may have any type of structure.

In the above example, even if the outside temperature drops abnormally, frost will not form on the outside air side heat exchanger 3 and the capacity will not decrease, and additionally, special heating equipment such as a boiler is not required. There is an advantage to not doing so.

The above describes how to allocate the refrigerant flow rate to the outside air side heat exchanger and the auxiliary heat exchanger when the outside air temperature changes, especially when the temperature becomes abnormally low, by adjusting the flow rate ratio according to the load within the normal capacity control range. This is an example in which capacity control is performed through control, but the present invention applies this method mutatis mutandis to perform capacity control in response to this even when the load is a small load that cannot be handled by normal capacity control. This is what made it possible.

An example thereof will be described. The structure of each part, load detection method, temperature detection method, refrigerant and load hot water flow path switching method, etc. are the same as in the above case.

When heating the load, the hot water outlet temperature detector 26, 3
2 or the like, and normal capacity control is performed in response to this detection.

When the load decreases to below a certain lower limit (20 to 50%), normal heat pump capacity control will no longer be able to cope with the problem. Therefore, when the temperature detector 32 is used as the load detection device, for example, as the temperature detection device, when the load detected by the temperature detector 32 becomes below the lower limit of this controllable range, a signal from the control mechanism 35 is sent. The bypass valve 21 is opened to an appropriate opening degree, and an amount of refrigerant corresponding to the load is guided to the auxiliary evaporator 23.

When the bypass valve 21 is opened, the refrigerant whose pressure is reduced by the expansion valve 22 flows into the auxiliary evaporator 23 and into the pipe 16.
It is heated by the hot water flowing through it and evaporates.
Therefore, the suction pressure of the compressor 1 increases, the outlet side pressure of the outside air side heat exchanger 3 also increases, and the saturation temperature in the outside air side heat exchanger 3 corresponding to this pressure also increases, so the temperature difference with the outside air increases. As a result, the amount of evaporation of the liquid refrigerant in the outside air side heat exchanger decreases, and the inflow heat from the outside air decreases.

However, since heat flows into the refrigerant from the load hot water in the auxiliary evaporator 23, in addition to the heat equivalent to the work of the compressor 1, the amount of heat given to the load fluid from the refrigerant side in the load side heat exchanger 7 is transferred to the bypass valve. 2
There is no change even if the refrigerant flow rate ratio according to 1 is changed.

However, the load fluid is cooled by the latent heat of vaporization of the refrigerant distributed to the auxiliary evaporator 23, and this cooled load fluid mixes with the load fluid heated by the load side heat exchanger 7 to cool it. and return it to the load.

That is, by increasing the flow rate of refrigerant distributed to the auxiliary evaporator 23 by the bypass valve 21, the temperature of the fluid sent to the load is further lowered. That is, the capacity of the heat pump can be made smaller than the minimum capacity in normal capacity control, resulting in the effect of widening the control range.

〔Effect of the invention〕

According to the present invention, even if the load is a small load that cannot be handled by normal capacity control, the heating capacity can be adapted to the load, and a heat pump device with a wide capacity control range can be provided, which is extremely large in practical use. be effective.

[Brief explanation of the drawing]

FIG. 1 is a flow diagram of an embodiment of the present invention. DESCRIPTION OF SYMBOLS 1...Compressor, 2...Four-way valve, 3...Outside air side heat exchanger, 4...Check valve, 5...Receiver, 6...Expansion valve, 7...Load side heat exchanger, 8...Check valve, 9...
Expansion valve, 10... Cooling medium cooler, 11... Jacket, 12... Pump, 13... Three-way valve, 14... Exhaust gas heat exchanger, 15... Three-way switching valve, 16... Auxiliary heat source path, 17... Three-way switching valve, 18... Three-way switching valve, 19
...Bypass path, 20...Solenoid valve, 21...Bypass valve, 22...Expansion valve, 23...Auxiliary evaporator, 24...Temperature detector, 25...Engine, 26, 27...Temperature detector, 28, 29...Pressure detector , 30, 31, 3
2... Temperature detector, 33, 34, 35, 36... Control mechanism, 37... Bypass path.

Claims (1)

[Scope of Claims] 1. A heat pump consisting of a compressor driven by a heat engine, an outside air side heat exchanger, a load side heat exchanger, an expansion device, and a refrigerant path connecting these devices;
In a heat pump device having a capacity control device that detects a load and controls capacity, an auxiliary evaporator is provided in the refrigerant path in parallel with the outside air side heat exchanger, and a load fluid is guided to the load side heat exchanger. a load fluid path, an auxiliary heat source path that guides the load fluid to the auxiliary evaporator, and a load detection device that detects the load;
The obtained detected value is compared with the set value, and when the load has decreased below the lower limit of a predetermined controllable range, the control is performed on the outside air side heat exchanger and the auxiliary evaporator based on the detected value. A heat pump device comprising: a flow rate ratio control device for controlling a refrigerant flow rate ratio. 2. The device according to claim 1, wherein the load detection device is a temperature detector that detects the temperature of the load fluid.