Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
  • F25B6/00—Compression machines, plants or systems, with several condenser circuits
  • F25B6/04—Compression machines, plants or systems, with several condenser circuits arranged in series
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
  • F25B30/00—Heat pumps
  • F25B30/02—Heat pumps of the compression type
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
  • F25B5/00—Compression machines, plants or systems, with several evaporator circuits, e.g. for varying refrigerating capacity
  • F25B5/02—Compression machines, plants or systems, with several evaporator circuits, e.g. for varying refrigerating capacity arranged in parallel
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
  • F25B2400/00—General features or devices for refrigeration machines, plants or systems, combined heating and refrigeration systems or heat-pump systems, i.e. not limited to a particular subgroup of F25B
  • F25B2400/24—Storage receiver heat
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
  • F25B40/00—Subcoolers, desuperheaters or superheaters
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
  • F25B40/00—Subcoolers, desuperheaters or superheaters
  • F25B40/04—Desuperheaters

Definitions

• the invention relates to a method for utilizing the specific residual heat of the coolant in a heat pump and a heat pump intended for carrying out this method, which is based on a coolant circuit in which a coolant evaporator for removing the heat of a gaseous or liquid medium to be cooled, a compressor for compressing the gaseous coolant, a condenser for liquefying the coolant and for transferring its conversion heat to a medium to be heated, the cooled side of a cooler and an expansion valve for reducing the pressure in the coolant are connected.
• the heat pumps are used to remove the heat energy from the medium to be cooled, usually air or water, and to transfer it to the medium to be heated, usually water in the central heating system or in a hot water tank. They are formed by a coolant circuit in which an evaporator, a compressor, a condenser and an expansion valve are connected. In the evaporator, the liquid coolant takes the heat corresponding to the heat of vaporization of the coolant from the pressure corresponding to the boiling point of approx. 0.1 MPa and below the temperature which is lower than that of the medium to be cooled.
• the evaporated coolant is then compressed in the compressor in such a way that the coolant is led out of the compressor under the pressure of about 1 to 3 MPa and under the temperature which is higher than that of the medium to be heated.
• the evaporated coolant condenses on the heat transfer surface of the condenser and transfers the latent amount of heat to the medium to be heated.
• the liquid coolant is fed into the expansion valve, in which its pressure and temperature are reduced in such a way that it evaporates in the evaporator while the heat is removed, and the medium to be cooled.
• the decisive criterion for assessing the efficiency of the heat pump is the so-called. Heating factor - ratio of the thermal power delivered to the medium to be heated at the outlet of the heat pump to the electrical power supplied to the heat pump.
• the heating factor depends on the temperature conditions in the evaporator and in the condenser. If, for example, the cooled medium is air at a temperature of -7 ° C and the water in the condenser is heated from 45 to 50 ° C, the manufacturers of the heat pumps state a heating factor of 2.12.
• a disadvantage of the known heat pumps is that the coolant is led from the condenser to the expansion valve at a temperature that is higher than the inlet temperature of the medium to be heated and that it consequently dissipates a considerable amount of heat that is not used in the system. In the example given, it is the specific heat that corresponds to the temperature difference between +45 and -7 ° C. Sometimes part of the remaining amount of heat in known heat pumps, see e.g. CZ 2000-2521 A3, removed from the coolant in a cooler located behind the condenser and e.g. used to heat service water.
• the invention is based on the object of designing a method for using the remaining specific heat in the coolant and a new heat pump which increases the heating factor by using the remaining amount of heat.
• a method for utilizing the residual specific heat of the coolant in a heat pump is proposed, which is based on a coolant circuit into which a coolant evaporator for removing the heat from a gaseous or liquid medium to be cooled, a compressor for compressing the gaseous coolant Condenser for liquefying the coolant and for transferring its heat of conversion to a medium to be heated, a cooled side of a cooler and an expansion valve for reducing the pressure in the coolant are connected.
• the coolant decreases the heat of vaporization of the filling of the container, in such a way that the filling of the container is circulated over a heat transfer surface until it gradually cools down to the temperature close to the temperature of the medium to be cooled, the evaporating Coolant flows over the other side of the heat transfer surface to the inlet of the compressor, and the pressure and thus the boiling point of the coolant are regulated in such a way that the temperature difference on the heat transfer surface corresponds to the temperature difference of the coolant and the medium to be cooled in the evaporator.
• This method can be carried out in a heat pump formed by a coolant circuit, into which a coolant evaporator for removing the heat from a gaseous or liquid medium to be cooled, a compressor for compressing the gaseous coolant, a condenser for liquefying the coolant and for transferring its conversion heat to one to be heated Medium, a cooled side of a cooler and an expansion valve to reduce the pressure of the coolant are switched.
• the heated side of the cooler is connected to a first heat transfer circuit, in which a first pump, a three-way valve and a heat transfer container are connected, the container being connected at the same time by means of the three-way valve to a second heat transfer circuit, in which, in addition to a second pump, a secondary to remove the heat, the liquid heat transfer medium is connected to certain evaporators, which can be switched alternately with the coolant evaporator in the coolant circuit.
• the heat transfer container is advantageously an elongated, vertically positioned vessel which is adapted to the change of the heat transfer filling without mixing it is. This enables the remaining specific heat to be stored in the heat transfer medium, the temperature of which changes in a relatively large interval.
• the coolant evaporator can serve as a secondary evaporator, as long as it is adapted for switching into a circuit of the liquid medium to be cooled and into the second heat transfer circuit. This advantageous embodiment saves a coolant evaporator.
• a third heat transfer circuit can be connected, which can be switched alternately by means of a three-way valve. This measure makes it possible to use part of the remaining amount of heat in the coolant after it has left the condenser in the period during which the heat transfer medium is not conducted into the container. This results in a further increase in the heating factor.
• a coolant circuit for carrying out the method according to the invention, in which a coolant evaporator for removing the heat from a gaseous or liquid medium to be cooled, a compressor for compressing the gaseous coolant, a condenser for liquefying the coolant and for transferring its conversion heat medium to be heated, a cooled side of a cooler and an expansion valve to reduce the pressure of the coolant, the remaining specific heat of the coolant can be used such that in the coolant circuit a cooled side of a secondary evaporator for heat exchange between two phases of the coolant, which for Line of the coolant is adapted substantially in the vertical direction, and its upper inlet on the cooled side with the outlet of the condenser and its lower outlet with the evaporator via the Expansion valve are switched, with a first circulation provided with a pump between the outlet and the inlet of the cooled side of the secondary evaporator and a second circulation between the outlet of the cooled side of the secondary e
• check valves are connected in the first circulation and also between the evaporator and the mouth of the second circulation.
• 1 is a schematic circuit diagram of a known heat pump
• FIG. 2 shows a heat circuit diagram of the heat pump according to FIG. 1.
• FIG. 3 shows a circuit diagram of the first embodiment of a heat pump according to the invention
• FIG. 4 and 5 are heat diagrams of the design of the heat pump according to FIG. 3 in the course of the first and the second period of its operating cycle
• Fig. 6 is a circuit diagram of the second embodiment of the heat pump, where the coolant evaporator alternately serves to remove the heat, the liquid medium to be cooled and the heat transfer medium, and
• Fig. 7 is a circuit diagram of the third embodiment of the heat pump, in which the remaining amount of heat in the coolant itself and in the walls of the heat transfer surfaces of the secondary evaporator is accumulated.
• 1, 3 and 6 is formed by a coolant circuit 1, in which a coolant evaporator 2, a compressor 3, a condenser 4 and an expansion valve 5 are connected.
• 6 is a medium to be cooled and 7 a medium to be heated by means of the heat pump.
• the heat pump is supplemented in comparison with FIG. 1 by a cooler 8, which is connected with its cooled side in the coolant circuit 1 behind the condenser 3 and with its heated side in the first heat transfer circuit 9.
• a first pump 10 a three-way valve 11 and a heat transfer container 12 are also connected in these.
• the container 12 is an elongated, vertically positioned vessel which is adapted to the change in the heat transfer filling without mixing it.
• the container 12 is simultaneously by means of Three-way valve 11 connected in a second heat transfer circuit 13.
• a secondary coolant evaporator 15 is connected in the second heat transfer circuit 13, the function of which is to remove the heat from the heat transfer medium.
• the secondary evaporator 15 is switched alternately with the evaporator 2 into the coolant circuit 1 by means of a second expansion valve 16.
• the medium 6 to be cooled is liquid, e.g. Is water, and is led to the cooled side of the evaporator 2 by means of a pipeline 17.
• the medium 6 to be cooled and the heat carrier circulating in the second heat carrier circuit 13 can be directed alternately to the cooled side of the evaporator 2.
• the second pump 14 can then be used alternately for the medium to be cooled and for the heat transfer medium. 6 is supplemented in comparison with the embodiment according to FIG.
• a third heat transfer circuit 19 is connected to the outlet of the first heat transfer circuit 9 from the cooler 8 and to the entry of the first heat transfer circuit 9 into the cooler 8, which can be switched alternately by means of a third three-way valve 20. This enables the heat from the cooler 8 to be conducted alternately into the first and second heat transfer circuits 9, 19.
• the heat pump according to the invention works cyclically: in a first time period, the heat transfer medium, which is almost heated in the cooler 8 to the temperature that the coolant leaving the condenser has, is passed into the container 12 by means of the first pump 10 until the container 12 with the Heat transfer medium of this temperature is completely filled.
• the coolant flows through the evaporator 2 during the first period of time.
• the three-way valve 11 closes the first heat transfer circuit 9 and opens the second heat transfer circuit 13. This begins a second time period during which the coolant circuit 1 is switched over in such a way that the coolant does not flow through the evaporator 2, but by the secondary evaporator 15 flows, thereby taking heat from the heat transfer medium.
• the temperature difference in the secondary evaporator 15 is kept such that it does not exceed approx. 5 ° C., ie that it basically corresponds to the difference in the evaporator 2 in the course of the first period.
• This is achieved by the circulation of the heat transfer medium in the second heat transfer circuit 13, in which the heat transfer medium, which has cooled in the secondary evaporator 15 by, for example, 5 ° C., is directed upwards into the container 12 and the liquid with the original temperature is pressed out of the container 12, without mixing with it.
• the new filling of the secondary evaporator 15 cools down by a further 5 ° C.
• the heat transfer medium in the second heat transfer circuit 13 and in the container 12 gradually cools down.
• the coolant pressure behind the expansion valve 16 is regulated so that the boiling point corresponds to the instantaneous temperature of the heat transfer medium.
• the electrical output of the compressor 3 remains the same in the first time period, that of the known heat pump, which operates under the same conditions and delivers the same thermal energy into the medium 7 to be heated. As a result, the heating factor is the same. In the heat pump according to the invention, however, the thermal energy is stored in the container 12. Because the evaporator 2 is supplied with the coolant with an energetic potential, reduced by the amount of heat given off in the cooler 8 and stored in the container 12 and the heat transfer area of the evaporator .; 2 is essentially not limited, the evaporating coolant absorbs a larger amount of heat from the medium 6 to be cooled than, under the same conditions, the coolant in the evaporator 2 of a known heat pump.
• the thermal energy stored in the container 12 is released into the primary coolant circuit 1 or into the secondary evaporator 15.
• the heat transfer takes place under the gradually decreasing temperature of the heat transfer medium and under the correspondingly regulated pressure behind the second expansion valve 16. Since the initial temperature in the secondary evaporator 15 is significantly higher than the temperature of the medium 6 to be cooled, the heating factor is also significantly higher. As the temperature of the heat transfer medium drops, the heating factor decreases gradually. It turns out, however, that the overall heating factor of the heat pump according to the invention is higher over the entire cycle than would be the case with a heat pump operating under the same conditions.
• the evaporator 2 In the heat pump according to Fig. 6, which is used to remove the thermal energy from a liquid stream, e.g. is designed from water, the evaporator 2 simultaneously performs the function of the secondary evaporator 15. On its cooled side, the three-way valve 18 leaves the medium 6 to be cooled, i.e. Flow water from a natural source, and in the second period the heat transfer medium from the tank 12. This measure does not lead to a change in the total heating factor of the heat pump in comparison with the version according to FIG. 3. Connection of the third heat transfer circuit 19, a further increase in the heating factor as a result: In the embodiment according to FIG. 3, the pump 10 is out of operation during the second time period and in the second heat transfer circuit 9 there is no circulation of the heat transfer medium.
• the pump 10 runs essentially continuously, the three-way valve 20 now directs the heat transfer medium into the third heat transfer circuit 19, e.g. a circuit for preheating the domestic water. Part of the remaining specific amount of heat is thus removed from the coolant in the cooler 8 even during the second period. As this increases the heat output of the heat pump at the outlet, its heating factor also increases.
• the proposed heat pump system according to FIG. 3 requires an expansion of the control compared to the known heat pump: the expansion valves 5, 16, the pumps 10, 14 and the three-way valve 11 should be switchable.
• the temperature of the heat transfer medium is measured at measuring points 22, 23 at the entries of the container 12. The determined values then serve to control the output of the pump 10 when the remaining amount of heat is removed from the cooler 8 and to control the Three-way valve 11 when switching between the first and the second period of the cycle.
• the secondary evaporator 15 is always connected with its cooled side into the coolant circuit 1 and is adapted to conduct the coolant in the essentially vertical direction. Its upper inlet 24 on the cooled side is connected to the outlet of the condenser 4 and its lower outlet 25 is connected to the evaporator 2 via the expansion valve 5.
• a first circuit 26 provided with a pump 27 is connected between the outlet 25 and the inlet 24 of the secondary evaporator 15.
• a second circuit 28 is connected between the outlet 25 of the secondary evaporator 15 and the inlet of the compressor 3.
• the second expansion valve 16 and the heated side of the secondary evaporator 15 are connected in the second circulation 28.
• the second circulation 28 enters and exits from the top of this.
• Check valves 29 are connected in the first circulation 26 and also between the evaporator 2 and the mouth of the second circulation 28.
• the time periods change very quickly: in the first time period, the coolant flows out of the condenser 4 via the cooled side of the secondary evaporator 15 and via the expansion valve 5 into the evaporator 2.
• the coolant the temperature of which is only a little is higher than that of the medium to be cooled 7 at the inlet of the condenser 4, gradually pushes the previous filling of the secondary evaporator 15 out on its cooled side and at the same time also heats the secondary evaporator 15 itself.
• the second period begins.
• the expansion valve 5 closes and the second expansion valve 16 opens.
• the refrigerant flowing through the latter evaporates on the heat transfer surface of the secondary evaporator 15 and the surface cools.
• the pump 27 and thus also the circulation in the first circulation 26 are started, so that the temperature difference on the cooled side of the secondary evaporator 15 remains small.
• the temperature of the liquid coolant on the cooled side of the secondary evaporator 15 and in the first cycle 26 gradually decreases.
• the pump 27 switches off, the second expansion valve 16 closes and the expansion valve 6 opens.
• the system returns to the operation characteristic of the first period. It is evident that the duration of the cycle is considerably shorter than that of the embodiment according to FIGS. 3 and 6 in view of the small circumferential and heat capacity of the secondary evaporator 15 or its cooled side.
• the goal of the calculation is to determine an overall heating factor of the heat pump according to the invention and to compare this with the known heating factor of a known heat pump.
• the calculation relates at best to a specific output of the heat pump, i.e. the medium to be heated is always supplied with 1 kW.
• the remaining power Pz in the form of the specific heat of the coolant is passed back from the condenser 4 via the expansion valve 5 into the evaporator 2.
• two power flows enter the evaporator 2: one from the medium 6 to be cooled and the other as the remaining power of the coolant. Their total corresponds to the total output that is used to change the physical state of the coolant. This can be done by two equations with two indefinites of which the remaining power P z is to be calculated.
• the remaining power that is not used in the known heat pump is 343.3 W.
• the heat dissipation from the coolant between the condenser and the expansion valve does not affect the electrical performance of the compressor.
• the output from the evaporator 2 in the form of the heat of conversion of the gaseous coolant must be constant while maintaining the overall output of the heat pump and its heating factor. Should the output decrease, the mass flow would also decrease and the value of the remaining output would change, but only by a relative value which corresponds to the ratio of the specific and conversion heat of the coolant and the temperature difference between the condenser 4 and the evaporator 2, and this would also change the power delivered to the evaporator 2 from the medium 6 to be cooled. Since the heat output of the heat pump is equal to the sum of the power supplied from the medium 6 to be cooled and the electrical power, the electrical power and consequently also the heating factor would also have to change in the event of such a change. However, this does not take place because the heating factor of a specific heat pump is dependent only on pressure conditions in front of and behind the compressor 3, these conditions only corresponding to the temperature conditions in the evaporator 2 and in the condenser 4.
• the heating factor would increase by approximately 34%. Because the efficiency of the use of the remaining power before This remaining output can only be used to a limited extent depending on the temperature difference when it is decreased.
• the heat pump according to the invention uses this remaining power indirectly. It works in a cycle divided into two periods. In the first period, the remaining power is efficiently removed with a large temperature difference and stored in the container 12, whereupon in the second period this stored energy from the container 12 is used instead of the energy of the medium 6 to be cooled. In the second period of the cycle, the heat pump operates with a higher heating factor because the temperature of the liquid discharged from the container 12 is higher than that of the medium 6 to be cooled.
• the duration of storage must be calculated. For this purpose, the total amount of energy stored in the container 12 and the remaining power of the heat pump used for storage are to be determined.
• the amount of energy stored depends on the mass of the container filling, the temperature difference during storage and the properties of the heat transfer medium.
• the remaining performance depends on the usable temperature gradient when stored in the container 12, the mass flow of the coolant and its physical properties.
• the duration (t A ) of the first period of the cycle results from simply dividing the heat capacity (E A ) of the container 12 by the stored remaining heat output.
• Container 12 capacity
• this time period no energy is taken from the medium 6 to be cooled, but the heat transfer medium from the container 12 is used as the energy source of the heat pump.
• a higher heating factor is achieved. Because this heating factor decreases during the cooling of the container 12 in the second time period, this time period is divided into 10 partial intervals only for the purpose of calculation. It is assumed that at the beginning the entire circumference of the container 12 has a temperature of 45 ° C., and further that the pump 10 in the circuit containing the cooled side of the secondary evaporator 15 and the container 12 has such a flow ensures that a constant temperature gradient of 5 ° C is maintained.
• a constant heating factor is calculated in each subinterval.
• the values of the heating factor are not certified, but are interpolated from a graph that was created according to various heat pump manufacturers under different conditions. Above all, the values for the first 3 subintervals were interpolated. The remaining values were taken from various sources and averaged.
• a calculation of the values of the first subinterval follows, for example.
• PE PTC - Pv [W; W, W]
• E E t v .
• Temperature gradient of the container 12 is the temperature difference between the container entry and exit during the subinterval. Decrease from the container 12 is the heat output in the secondary
• Evaporator 15 flows from the heat transfer medium into the coolant.
• the duration of the subinterval is the time during which the entire filling of the container 12 flows through the secondary evaporator and is thereby cooled by 5 ° C.
• Electrical power is the electrical power of the heat pump, i.e. of
• Compressor 3 Electrical energy is the electrical energy supplied to the heat pump during the sub-interval. The energy obtained is the medium 7 to be heated
• the heating factor has increased from 2.12 to 2.53 , which is an increase of 19%.

Landscapes

• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Mechanical Engineering (AREA)
• Thermal Sciences (AREA)
• General Engineering & Computer Science (AREA)
• Heat-Pump Type And Storage Water Heaters (AREA)
• Compression-Type Refrigeration Machines With Reversible Cycles (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=27762286

Family Applications (1)

Country Status (2)

Cited By (2)

Families Citing this family (1)

Citations (5)

• 2002
  • 2002-02-26 CZ CZ2002693A patent/CZ2002693A3/cs not_active IP Right Cessation
• 2003
  • 2003-02-25 WO PCT/CZ2003/000014 patent/WO2003073020A1/de not_active Ceased

Patent Citations (5)

Also Published As

Similar Documents

Legal Events