HK1147795B - Heat pump device - Google Patents

Description

Heat pump device

Technical Field

The present invention relates to a device for heating and cooling, respectively. More particularly, the invention relates to such devices comprising a heat pump.

Background

Heat pumps are often used for heating and/or cooling. Such a heat pump has two sides, a warm side and a cold side. In so-called reversible heat pumps, these two sides can be changed so that the warm side becomes the cold side and vice versa. This is useful if the heat pump is to be operated at different times for heating and cooling.

In a closed system, a cooling medium flows between two sides in such a heat pump. Each side is thermally connected to an outer loop, through which the heat carrier flows, via a respective heat exchanger. The term "heat carrier" is used herein for a liquid that is capable of transferring thermal energy from one location to another when the liquid is transported between two locations. In other words, the heat carrier can carry heat or cold. In one example of such a system, the first outer loop comprises a borehole for geothermal heating, and the first outer loop is thermally connected to the cold side of the heat pump. The second outer loop includes a heating system used in, for example, a building, and is thermally connected to the warm side of the heat pump.

In these systems, at least two separate circuits are thus provided, each requiring a refill device and an expansion tank or the like. Therefore, a large number of components are required to manufacture these systems. This leads to increased costs due to unnecessarily poor production reliability and unnecessarily high requirements on maintenance. Furthermore, because a separate pressure sensor is required in each separate loop, operational monitoring is more difficult. In addition to this, the system start-up becomes complicated, since the heat carrier has to be filled at several different locations.

In conventional systems for heating and cooling houses, there is often a risk of freezing in the loop connected to the cold side of the heat pump during cooling operation, since the cooling medium in the house is kept at a comparatively low temperature and is further cooled when in contact with the heat exchanger against the cold side of the heat pump, and since the cooling medium often comprises water to which no antifreeze is added.

Furthermore, when the heat pump is in operation, the external circuit receiving thermal energy from the heat exchanger must in these systems always operate at a constant flow of heat carrier, in order to avoid damage to the heat exchanger due to overheating. This is a problem since systems for heating indoor air in e.g. buildings are usually connected to one or more temperature regulators which switch off the external thermal energy absorption loop when the desired air temperature is reached. Therefore, the heat pump must also be shut down so as not to be damaged, resulting in a reduction in overall system efficiency. Moreover, repeated switching on and off increases wear on the heat pump.

Disclosure of Invention

The present invention solves the above problems.

Thus, the invention relates to a device for heating and cooling, respectively, said device comprising: a heat pump; a first heat exchanger arranged at a first side of the heat pump, the first heat exchanger being thermally connected to a first heat carrier, the first heat carrier circulating in a first loop; and a second heat exchanger arranged at the second side of the heat pump, which second heat exchanger is arranged to transfer thermal energy to or from a second heat carrier, which second heat carrier circulates in a second loop, and that the arrangement is characterized in that the first loop and the second loop are connected to each other by means of a conduit, so that the first loop, the second loop and the conduit together form a connecting system in which the same heat carrier is arranged.

Drawings

The invention will be explained in more detail hereinafter with reference to exemplary embodiments of the invention and with reference to the accompanying drawings, in which:

fig. 1 is a schematic overview of the device according to the invention.

Detailed Description

The heat pump 1 comprises two sides, a warm side and a cold side. On either side, a first heat exchanger 2 and a second heat exchanger 3 are arranged, respectively. The heat pump 1 is of the liquid-liquid type, meaning that the heat pump 1 is arranged to transfer thermal energy between two liquid heat carriers.

According to a preferred embodiment, the heat pump 1 is reversible, meaning that the heat pump 1 can be used for both heating and cooling. Depending on the mode of operation selected, either of the two sides may be the cold side. During the heating operation, the first heat exchanger 2 side is the cold side and the second heat exchanger 3 side is the warm side, and the opposite is true during the cooling operation.

In other words, the heat pump 1 is arranged to be able to transfer thermal energy from the first heat exchanger 2 side to the second heat exchanger 3 side, and the opposite way is also possible. For such a heat pump, it is preferred that the first heat exchanger 2 is arranged with the same capacity as the second heat exchanger 3 in order to achieve better installation, operation and maintenance economy. Such a heat pump arrangement is previously known from swedish patent 0602688-4, which is hereby incorporated by reference in its entirety.

The first heat exchanger 2 is thermally connected to the first loop 10 in the form of a pipework. In the first loop 10, a heat carrier is circulated by using a pump device 12 known per se.

According to a preferred embodiment, the first loop 10 conveys the heat carrier downwards into the energy trap 13 and upwards from the energy trap 13. It will be appreciated that the energy trap 13 may take many different forms, such as a loop buried under water in a lake or in the ground, or in the form of a hole dug or drilled in the ground. When the energy trap 13 is warmer than the first heat exchanger 2 side of the heat pump 1, the heat carrier thus transfers thermal energy from the energy trap 13 to the heat pump 1 by circulating in the first loop 10 using the pump device 12. Correspondingly, if the energy sink 13 is colder than the first heat exchanger 2 side of the heat pump 1, the heat carrier transfers thermal energy from the heat pump 1 to the energy sink 13.

Furthermore, the second heat exchanger 3 is thermally connected to the second loop 20 in the form of pipework. A second pump device 22, known per se, is arranged to circulate the heat carrier in the second loop 20.

When the heat carrier 1 is set to a heating operation, i.e. transfer of thermal energy from the first heat exchanger 2 to the second heat exchanger 3, the thermal energy is transferred from the energy trap 13 to the first heat exchanger 2 and continues to the second heat exchanger 3 by the heat pump action and further to the heat carrier in the second loop 20. In this case, the added thermal energy may be used to heat a building (not shown), for example tap water and/or indoor air.

On the other hand, when the heat pump 1 is set to a cooling operation, i.e. thermal energy is transferred from the heat carrier in the second loop 20 to the energy sink 13 via the heat pump 1 and the heat carrier in the first loop 10, the cooled heat carrier may be used to cool the building, for example cooling the indoor air.

The second loop 20 includes a first additional heat exchanger 31 and a second additional heat exchanger 41. The first additional heat exchanger 31 is thermally connected to a hot water tank 30 for tap water. The second additional heat exchanger 41 is thermally connected to an energy buffer device 40, said energy buffer device 40 comprising a tank with a heat carrier. The volume of the tank is of sufficient size for adequate buffering of thermal energy in practical applications. The heat carrier in the buffer device 40 may be water, for example.

Since the second pump device 22 is arranged to circulate the second heat carrier in the second loop 20, thermal energy can thus be transferred between the heat pump 1 and the additional heat exchanger 31, 41 via the second loop 20.

During operation, heat carrier in the second loop 20 circulates according to arrow A, B. Furthermore, the control device 23 controls the valve apparatus 21 so as to: the flow of the heat carrier in the second loop 20 is controlled according to arrow F, C, whereby the heat carrier is led to the second additional heat exchanger 41; or the flow of the heat carrier in the second loop 20 is controlled according to arrow D, E, whereby the heat carrier is led to the first additional heat exchanger 31. The valve device 21 may comprise, for example, a conventional adjustable three-way valve.

The control means 23 controls the valve arrangement 21 on the one hand on the basis of whether the heat pump 1 is operating in the heating mode or in the cooling mode and on the other hand on the basis of whether a temperature regulator or a temperature sensor 42 arranged in the thermal buffer means 40 and connected to the control means 23 indicates that the temperature in the thermal buffer means 40 exceeds a predetermined value.

According to a preferred embodiment, the heat carrier is mainly directed to the second heat exchanger 41 when the heat pump 1 is operating in heating mode, i.e. when the heat pump 1 transfers thermal energy from the first loop 10 to the second loop 20. When the thermostat 42, which continuously monitors the temperature in the energy buffer device 40, measures a temperature that exceeds a predetermined value, the thermostat 42 sends a signal to the control device 23, which control device 23 in turn controls the valve arrangement 21 to direct the heat carrier to the first heat exchanger 31. The predetermined value may be set during manufacture or installation, or may be adjustable. Thus, during a heating operation, thermal energy is transferred to the energy buffering device 40 as long as the temperature of the energy buffering device 40 is at least as low as a predetermined value. Otherwise, thermal energy is transferred from the heat pump 1 to the hot water tank 30, said hot water tank 30 thereby also acting as an energy buffer. The hot water tank 30 further comprises a temperature regulator 32, said temperature regulator 32 sending a signal to the control means 23 in a corresponding manner to the temperature regulator 42 when the temperature in the hot water tank 30 exceeds a certain predetermined value. When this occurs, the control device 23 may temporarily set the system to the shut-off state.

During heating operation, this arrangement enables the heat pump 1 to operate with substantially less frequent switching on and off than conventional systems, despite the thermostat 42 serving to maintain a uniform temperature level in the energy buffer device 40. Thereby, problems with overheating and losses in the heat pump 1 are reduced, said heat pump 1 can be operated more smoothly, which also results in a system with a higher overall efficiency. Since the heat pump 1 does not have to be set intermittently in order to regulate the heat production during operation, a smoother operation of the system is also achieved.

On the other hand, when the heat pump 1 is operating in cooling mode, i.e. when the heat pump 1 transfers thermal energy from the second loop 20 to the first loop 10, the heat carrier is always led to the second heat exchanger 41. Thus, in this case, the heat carrier transfers thermal energy from the energy buffer device 40 to the heat pump 1, whereby the energy buffer device 40 is cooled.

The energy buffer device 40 is connected to a thermocouple device 43, and said thermocouple device 43 is controlled by the control device 23. For example, the thermocouple arrangement 43 may comprise a closed system of suitable, conventional pipework and heat exchangers, in which the heat carrier is circulated using a pump arrangement (not shown), and the heat carrier is arranged to transfer thermal energy optionally between the energy buffer device 40 and a first distribution system 44 for heat or a second distribution system 45 for cold.

The first distribution system 44 may be, for example, a liquid-based system for distributing heat to rooms in a building, such as a system with a water-filled radiator or a system with water-borne underfloor heating, but may also be a system that transfers heat by using a fan coil unit.

In a similar manner, the second distribution system 45 may be a liquid-based system for distributing cold to a building.

Thus, during a heating operation, the heat pump 1 will transfer thermal energy to both the hot water tank 30 and the energy buffer means 40, from which hot water tank 30 tap water, for example for domestic use in a house, can be taken out. In this case, the control device 23 controls the thermocouple device 43 to distribute the thermal energy from the energy buffer device 40 to the first distribution system 44 for heat, in order to thereby heat the building. The thermal energy that is not needed for heating the building will be directed to the hot water tank 30 due to the temperature regulation.

During cooling operation, the heat pump 1 will absorb thermal energy from the energy buffer device 40, so that the heat carrier therein is cooled. In this case, the control device 23 controls the thermocouple device 43 to let the second distribution system 45 for cold absorb thermal energy from the house and the transfer device 40 for further transfer to the heat pump 1.

If it is desired to cool the building simultaneously with heating the tap water, it is of course possible to let the heat pump 1 alternate between heating and cooling operations, thereby transferring thermal energy alternately from the heat pump 1 to the hot water tank 30 and from the energy buffer device 40 to the heat pump 1.

According to a preferred embodiment, both distribution systems 44, 45 are of the cryogenic type. This means that during heating and cooling, the temperature difference between the air being heated or cooled and the heat carrier in the active distribution system for heat and cold, respectively, is low. Furthermore, in these climatic zones described above, this means that the temperature difference between the energy buffer device 40 (and thus the second loop 20) and the first loop 10 is low, which in turn results in a high efficiency of the heat pump 1.

Preferably, the temperature difference between the first loop 10 and the second loop 20 is as low as possible, since this results in better efficiency during heating and cooling.

As shown in fig. 1, the first loop 10 is connected to the second loop 20 by using a pipe 4. Thereby, a connection system is formed comprising the first loop 10, the second loop 20 and the conduit 4, with the conduit 4 acting as a bridge therebetween. In this system, only one common heat carrier is thus arranged. The common heat carrier may be in any suitable form, such as water with conventional antifreeze additives.

The inner diameter of the conduit 4 is small compared to its length. More specifically, the diameter is so small that circulation of the heat carrier between the first loop 10 and the second loop 20 is substantially prevented when the first loop 10 and the second loop 20 are filled with the heat carrier to a level above the conduit 4. In other words, substantially no heat carrier flows from the first loop 10 to the second loop 20, or vice versa. The term "substantially free of heat carrier" means that, in the event of a relative pressure variation due to heating and/or cooling of the heat carrier in the loops 10, 20, a small amount of heat carrier may flow between the two loops 10, 20, respectively, but that, in addition, during operation, only a negligible amount of heat carrier flows between the loops 10, 20 for operation of the system.

According to a preferred embodiment, the catheter is at least 50cm long and has an inner diameter of at most 10 mm.

The conduit 4 has a pressure equalization effect between the first loop 10 and the second loop 20. This results in the advantage that only one expansion vessel 14 is required for the operation of both circuits 10, 20, which means that it is simplified compared to similar known systems.

Furthermore, due to this arrangement, only one refill device 5 is required for filling the circuits 10, 20 with the heat carrier. Preferably, a refilling device 5 known per se is arranged along the loop 10, and by means of the refilling device 5 the heat carrier can be simultaneously filled to the first loop 10 and thus also to the second loop 20 via the conduit 4. This not only means a simplification compared to similar known systems, but also the filling procedure can be performed faster.

For ventilation of the system, at least one ventilation valve (not shown) is arranged. Depending on the application at hand, ventilation valves may also be arranged in both the first loop 10 and the second loop 20.

In order to monitor the loops 10, 20, only one pressure sensor is required, since there is substantially the same pressure in both loops 10, 20.

Finally, the above-described arrangement with the connecting conduit 4 solves the problem of the risk of freezing in the second loop 20, since the same heat carrier is used in the second loop 20 as in the first loop 10. Thus, since the heat carrier used in the first loop 10 must be frost-resistant, this also applies to the heat carrier in the second loop 20, which is why there will be no risk of freezing in the second loop 20 during the cooling operation. Preferably, the common heat carrier is freeze-protected down to at least-10 ℃. For example, the heat carrier may comprise water with 30% ethanol.

In the above, preferred embodiments have been described. However, it will be apparent to those skilled in the art that various modifications can be made to the described embodiments without departing from the spirit of the art. Thus, the invention should not be limited by the described embodiments, but may be varied within the scope of the invention.

Claims (10)

1. An apparatus for separately heating and cooling, comprising: a heat pump (1); a first heat exchanger (2) arranged at a first side of the heat pump (1), the first heat exchanger (2) being thermally connected to a first heat carrier, which circulates in a first loop (10); and a second heat exchanger (3) arranged at a second side of the heat pump (1), the second heat exchanger (3) being arranged to transfer thermal energy to or from a second heat carrier circulating in a second loop (20), characterized in that the first loop (10) and the second loop (20) are interconnected by means of a conduit (4) such that the first loop (10), the second loop (20) and the conduit (4) together form a connection system in which the same heat carrier is arranged and the inner diameter of the conduit (4) is sufficiently small relative to the length of the conduit (4) such that circulation of heat carrier between the first loop (10) and the second loop (20) is substantially prevented.

2. The arrangement according to claim 1, characterized in that the heat pump (1) is a reversible heat pump arranged to be able to transfer thermal energy from its first side to its second side and further arranged to be able to transfer thermal energy from its second side to its first side.

3. The arrangement according to claim 2, characterized in that the first heat exchanger (2) has the same capacity as the second heat exchanger (3).

4. An arrangement according to claim 1, characterised in that the first loop (10) is arranged for transferring thermal energy between an energy sink (13) and the heat pump (1) by means of a first pump arrangement (12), which first pump arrangement (12) is arranged to circulate the first heat carrier in the first loop (10).

5. An arrangement according to claim 1, characterised in that the second circuit (20) comprises at least one additional heat exchanger (31; 41), whereby the second circuit (20) is arranged to transfer thermal energy between the heat pump (1) and the additional heat exchanger (31; 41) by using a second pump device (22), which second pump device (22) is arranged to circulate the second heat carrier in the second circuit (20).

6. An arrangement according to claim 5, characterised in that the second loop (20) comprises a first additional heat exchanger (31), a second additional heat exchanger (41) and a valve arrangement (21), the first additional heat exchanger (31) being thermally connected to the hot water tank (30), the second additional heat exchanger (41) being thermally connected to an energy buffer device (40), wherein the control device (23) is arranged to control the valve arrangement (21) such that the second heat carrier is led to the first additional heat exchanger (31) or to the second additional heat exchanger (41) when the heat pump (1) is set to transfer thermal energy from its first side to its second side, and the control device (23) is arranged to control the valve arrangement (21) such that when the heat pump (1) is set to transfer thermal energy from its second side to its first side, the second heat carrier is led to the second additional heat exchanger (41).

7. An arrangement according to claim 6, characterized in that a thermocouple arrangement (43) is arranged to transfer thermal energy from the energy buffer arrangement (40) to a first distribution system (44) for heat when the arrangement for heating and cooling, respectively, is set to heating mode operation, and that the thermocouple arrangement (43) is arranged to transfer thermal energy from a second distribution system (45) for cold to the energy buffer arrangement (40) when the arrangement for heating and cooling, respectively, is set to cooling mode operation.

8. The device according to claim 7, characterized in that said first distribution system for heat (44) and said second distribution system for cold (45) are of the cryogenic type.

9. An arrangement according to claim 1, characterized in that the first loop (10) and the second loop (20) together comprise only a single expansion vessel (14).

10. An arrangement according to claim 1, characterised in that the first loop (10) is arranged with a refill device (5), which refill device (5) is arranged to allow simultaneous filling of heat carrier into the first loop (10) and the second loop (20).