Climate Control Unit and System Comprising the Same

Abstract

The present application concerns a climate control unit for controlling air temperature and/or humidity. Moreover, the present application concerns a system comprising such a climate control unit.

The climate control unit according to the invention makes uses of two refrigerant paths that share a common part in which a compressor and evaporator are arranged, and that each have a non-shared part. A reheat coil is provided in one of the non-shared parts. According to the invention, a respective expansion device is provided in both non-shared parts.

Claims

1. A climate control unit for controlling air temperature and humidity, comprising: a reheat coil; a compressor; an evaporator having an output that is connected to an input of the compressor, the climate control unit being configured to be coupled to a condenser for outputting thermal energy, wherein the climate control unit, when coupled to the condenser, forms a refrigerant circuit together with the condenser; and a first expansion device arranged in a first refrigerant path and configured to control a flow of the refrigerant in that path, wherein the climate control unit further comprises a second expansion device configured to control a flow of the refrigerant in a second refrigerant path, wherein the first and second refrigerant paths share a common part and each have a respective individual part, and in that the first and second expansion devices are arranged in the individual parts of the first and second refrigerant paths, respectively, wherein the first refrigerant path extends between an output of the compressor and an input of the evaporator through the condenser, and wherein the second refrigerant path extends between the output of the compressor and the input of the evaporator through the reheat coil, and wherein the reheat coil is arranged inside the individual part of the second refrigerant path.

2. The climate control unit according to claim 1, wherein the first and/or second expansion device is an electronic expansion valve (EEV) or a thermostatic expansion valve (TXV).

3. The climate control unit according to claim 1, wherein the condenser is air-cooled or water-cooled.

4. The climate control unit according to claim 1, wherein the first expansion device is arranged in between the condenser and the input of the evaporator, and wherein the second expansion device is arranged in between the reheat coil and the input of the evaporator.

5. The climate control unit according to claim 1, wherein the second refrigerant path extends between the output of the compressor and the input of the evaporator through the condenser and through the reheat coil in that order.

6. The climate control unit according to claim 5, further comprising an outlet connected to the output of the compressor and connectable to an inlet of the condenser, and an inlet connectable to an outlet of the condenser and connected, via a T-junction, to an input of the reheat coil and to an input of the first expansion device.

7. The climate control unit according to claim 1, wherein the condenser is arranged in the individual part of the first refrigerant path.

8. The climate control unit according to claim 7, further comprising an outlet connectable to an inlet of the condenser, wherein an output of the compressor is connected, via a T-junction, to the outlet and to an input of the reheat coil, and an inlet connected to the first expansion device and connectable to an outlet of condenser.

9. The climate control unit according to claim 6, further comprising a controller for controlling the compressor and the first and second expansion devices.

10. The climate control unit according to claim 9, further comprising an inverter for supplying power to the compressor, and wherein controlling the compressor comprises controlling the amount of power supplied by the inverter to the compressor.

11. The climate control unit according to claim 9, further comprising a first sensing unit for sensing a temperature and a pressure of the refrigerant between the output of the evaporator and the input of the compressor, wherein the controller is configured to control the first and second expansion devices in dependence of the refrigerant temperature and/or pressure.

12. The climate control unit according to claim 11, wherein the first sensing unit is arranged at the output of the evaporator.

13. The climate control unit according to claim, wherein the controller is configured to calculate a superheat of the system based on the sensed temperature and pressure, to control the first and/or second expansion devices to ensure that the superheat remains above a first positive threshold, said calculating the superheat preferably comprising subtracting a boiling point of the refrigerant from the sensed temperature of the refrigerant.

14. The climate control unit according to claim 13, wherein the boiling point of the refrigerant is determined by looking up said boiling point of the refrigerant corresponding to the sensed pressure of the refrigerant in a look-up table.

15. The climate control unit according to claim 13, further comprising: a user input module in which a user can select a desired air temperature and/or humidity; a ventilator which can be activated by the controller, and which, when activated, causes a first airflow which passes through the evaporator and the reheat coil, in that order; and a second sensing unit for sensing a temperature and/or humidity of the air in the first airflow upstream of the evaporator and/or a third sensing unit for sensing a temperature and/or humidity of the air in the first airflowdownstream of the evaporator preferably downstream of the reheat coil, wherein the controller is configured, at least during operation, to control the compressor and the first and second expansion devices in dependence of at least one of the air temperature and/or humidity sensed by the second sensing unit, the air temperature and/or humidity sensed by the third sensing unit, the sensed refrigerant pressure and/or temperature, the desired temperature and the desired humidity.

16. The climate control unit according to claim 15, wherein the controller is configured to operate the climate control unit in a cooling mode, in which mode the controller: controls the power supplied to the compressor to control the cooling power of the climate control unit in dependence of the desired temperature and the temperature of the air as sensed by the second and/or third sensing unit; ensures a closed state of the second expansion device; and controls the first expansion valve to ensure that the superheat remains positive.

17. The climate control unit according to claim 16, wherein the controller is configured to operate the climate control unit in the cooling mode if the temperature of the air is above the desired temperature and if the humidity of the air is at or below the desired humidity regardless of the resulting dehumidification.

18. The climate control unit according to claim 16, wherein the controller is configured to operate the climate control unit in a dehumidifying mode in which mode the controller: controls the power supplied to the compressor to control the dehumidification power of the climate control unit in dependence of the desired humidity and the humidity of the air as sensed by the second and/or third sensing unit; ensures a closed state of the first expansion device; and controls the second expansion device to ensure that the superheat remains positive.

19. The climate control unit according to claim 18, wherein the controller is configured to operate the climate control unit in the dehumidification mode if the temperature of the air is at or below the desired temperature and if the humidity of the air is above the desired humidity.

20. The climate control unit according to claim, wherein the controller is configured to operate the climate control unit in a hybrid mode in which mode the controller: controls the power supplied to the compressor to control the dehumidification power of the climate control unit in dependence of the desired humidity and the humidity of the air as sensed by the second and/or third sensing unit; and controls the ratio of refrigerant flowing through the first and second expansion device to keep the cooling power constant.

21. The climate control unit according to claim 20, wherein the controller is configured to switch from the cooling mode to the hybrid mode if the temperature of the air has decreased, during the cooling mode, to a value within a predefined range of the desired temperature and if the sensed humidity of the air sensed by the second and/or third sensing unit is above the desired humidity and/or if a desired humidity has not been inputted.

22. A system, comprising: a climate control unit as defined in claim 6; and a condenser having an inlet and an outlet connected to the outlet and the inlet of the climate control unit, respectively.

Description

[0029] Further advantages, features and details ofpossible embodiments of the climate control unit will be elucidated on the basis of the following description of the accompanying figures, wherein:

[0030] FIG. 1 shows a schematic representation of a climate control system comprising a possible embodiment of a climate control unit according the present invention in which a gas reheat configuration is used; and

[0031] FIG. 2 shows a schematic representation of a climate control system comprising a further possible embodiment of a climate control unit according the present invention in which a liquid reheat configuration is used.

[0032] The system of FIG. 1 is a possible embodiment of a climate control system 100 according to the present application, in which a climate control unit 10 is arranged to function as a gas-reheat system. System 100 comprises a climate control unit 10 that is typically arranged in an enclosed space to be cooled, e.g. a room, and a condenser 3 that is typically arranged outside of the enclosed space or is embodied as a water-cooled condenser.

[0033] In the refrigerant circuit of system 100, two refrigerant paths can be identified. In the first path, starting from evaporator 1, the refrigerant passes through a compressor 4, through condenser 3, and through a first electronic expansion valve K1 before returning to evaporator 1.

[0034] In this first path, the refrigerant leaving evaporator 1 should be completely gaseous to avoid damaging compressor 4. It should therefore be ensured that the temperature of the refrigerant is at or above the boiling point of the refrigerant. To measure this temperature, climate control unit 10 is provided with a first sensing unit 9 between evaporator 1 and compressor 4. The amount that the measured temperature is above the boiling point of the refrigerant is called the superheat. It is preferred that this superheat is kept as low as possible to optimize the efficiency of system 100.

[0035] Compressor 4 compresses the low-pressure, relatively cold gaseous refrigerant into a high-pressure, hotter gaseous refrigerant. In condenser 3, this high-pressure, hot gaseous refrigerant is cooled because thermal energy is outputted by condenser 3 to the outside, e.g. outside air. More in particular, the gaseous refrigerant condenses into a high-pressure, warm liquid refrigerant. In electronic expansion valve K1, the high-pressure, warm liquid refrigerant is expanded and a low-pressure, colder mixture of liquid/gas refrigerant is provided to evaporator 1.

[0036] In evaporator 1, the low-pressure, colder refrigerant absorbs thermal energy from the air that passes by evaporator 1 causing the refrigerant to evaporate. Therefore, evaporator 1 will output a low-pressure, cold gaseous refrigerant after which the abovementioned cycle may continue.

[0037] In the second path, starting from evaporator 1, the refrigerant passes through compressor 4, through a reheat coil 2, and through a second electronic expansion valve K2 before returning to evaporator 1. In the second refrigerant path, the mixture that is cooled by evaporator 1 is reheated by the relatively hot refrigerant that passes through reheat coil 2. In this manner, moisture can be extracted from the ambient air, by means of condensation on evaporator 1, while at the same time preventing excessive cooling of the air.

[0038] The second refrigerant path shares a part with the first refrigerant path, namely the part of the refrigerant circuit comprising evaporator 1 and compressor 4. The parts of the refrigerant circuit that are not shared by the first and second paths are indicated as the first and second individual parts, respectively. The shared part of the first and second paths is connected to a T-junction 6A that is arranged directly after compressor 4. This T-junction splits the incoming refrigerant flow from compressor 4 into the first and second individual parts and directs refrigerant to both the input of condenser 3 and the input of reheat coil 2. The respective individual parts are joined later at the input of evaporator 1.

[0039] In reheat coil 2, the high-pressure, hot gaseous refrigerant coming from compressor 4 is cooled due to the cold air coming from evaporator 1. In electronic expansion valve K2, the high-pressure, cold mixture of liquid/gas refrigerant is expanded and a low-pressure, colder liquid refrigerant is outputted. Similar to expansion device K1, expansion device K2 may output a mixture of refrigerant in the gaseous and liquid states.

[0040] In the system shown in FIG. 1, condenser 3 is connected to climate control unit 10. More in particular, an inlet for condenser 3 is connected to an outlet 7A of climate control unit 10 and an outlet of condenser 3 is connected to an inlet 7B of climate control unit 10. Outlet 7A is connected to one of the outputs of T-junction 6A and inlet 7B is connected to electronic expansion valve K1.

[0041] Furthermore, climate control unit 10 comprises a ventilator or fan 5A arranged in such a manner that, when activated, ventilator 5A causes a first airflow Al in which air is moved through evaporator 1 and through reheat coil 2. It should be noted that evaporator 1 and reheat coil 2 can both be embodied substantially identical, e.g. as a coil unit through which air may pass. As mentioned earlier, in evaporator 1, thermal energy is absorbed by the refrigerant from the air. Moreover, as mentioned earlier, in reheat coil 2, heat is transferred from the refrigerant to the air passing through reheat coil 2. The air that has passed through reheat coil 2 is supplied to the surrounding environment. To measure the temperature and/or humidity of the outgoing air, a sensing unit 11 is installed in airflow path Al downstream of evaporator 1 and reheat coil 2. Similarly, to measure the temperature and/or humidity of the incoming air, which is representative for the temperature in the enclosed space to be cooled, a sensing unit is 13 is installed in airflow path A1 downstream of evaporator I and reheat coil 2.

[0042] Furthermore, condenser 3 may comprise a second ventilator or fan 59 arranged in such a manner that, when activated, ventilator 5B causes a second airflow A2 in which air is moved through condenser 3. This will increase the capacity with which condenser 3 is able to exchange heat with its surroundings, typically outside of the enclosed space to be cooled.

[0043] Climate control unit 10 comprises a controller 8 for controlling the active elements, i.e. ventilator 5A and first and second electronic expansion valves K1, K2. If controller 8 is connected to condenser 3, it may also control ventilator 5B. Furthermore, a user input unit 12 may be provided by which a user may input a desired temperature and'or humidity.

[0044] The system of FIG. 2 is another possible embodiment of a climate control system 200 according to the present application, in which a climate control unit 20 is arranged to function as a liquid-reheat system. System 200 comprises a climate control unit 20 that is typically arranged in an enclosed space to be cooled, e.g. a room, and a condenser 3 that is typically arranged outside of the enclosed space.

[0045] In the refrigerant circuit of system 200, again two refrigerant paths can be identified. The first path through the refrigerant circuit is similar to the first path in FIG. 1.

[0046] The second path, however, is different in this embodiment. Starting from evaporator 1, the refrigerant passes through compressor 4, through condenser 3, through reheat coil 2, and through electronic expansion valve K2 before returning to evaporator 1.

[0047] The part of the second refrigerant path that is shared with the first refrigerant path now comprises evaporator 1, compressor 4 and condenser 3. Again, the parts of the refrigerant circuit that are not shared by the first and second paths are defined as the first and second individual parts, respectively. A T-junction 6B is connected directly after condenser 3 and directs an incoming refrigerant stream to both electronic expansion valve K1 and the input of reheat coil 2. The respective individual parts are joined later at the input of evaporator 1.

[0048] Condenser 3 is connected to climate control unit 20. More in particular, an inlet for condenser 3 is connected to an outlet 7C of climate control unit 20 and an outlet of condenser 3 is connected to an inlet 7D of climate control unit 20. Outlet 7C is connected to the output compressor 4 and inlet 7D is connected to the input of T-junction 6B.

[0049] The other components of system 200 are identical to those of system 100 and a further explanation is therefore considered redundant.

[0050] If condenser 3 is a water-cooled model, condenser 3 is not, necessarily arranged outside of the enclosed space to be cooled. Instead, a cold water supply is provided to the water-cooled condenser. In this embodiment, one or more water flow valves may be provided to enable a flow of water and hereby provide a similar functionality as ventilator 5B in the abovementioned embodiments. Moreover, the climate control unit may be manufactured with said condenser included the climate control unit itself. The refrigerant paths as defined before are maintained. However, such an embodiment does not necessarily require the inlet/outlet structure. Such water-cooled models do not rely on outdoor circumstances, which is advantageous, since if a temperature outside of the space to be heated the becomes too cold, then the pressure within condenser 3 may decrease, which will cause too much refrigerant to migrate to condenser 3 when K1 is fully closed.

[0051] Next, an operation cycle will be described in which a user has inputted a desired temperature of 20 degrees and a desired humidity of 40% for a room that has an initial temperature of 25 degrees and a humidity of 70%. This operational cycle will be described referring to the gas-reheat configuration shown in FIG. 1. It should be noted that the values provided next only serve to illustrate the working principles of the invention and should not be construed as limiting the invention to these values only.

[0052] First, controller 8 will operate climate control unit 10 in a mode referred to as cooling mode. In this mode, controller 8 will control the cooling power of the climate control unit based on the desired temperature and at least one of a temperature measured by sensing unit 11 and a temperature measured by sensing unit 13. Furthermore, controller 8 will close expansion valve K2 and control expansion valve K1 to maintain a minimal super heat. More in particular, controller 8 can control an inverter 14 which provides power to compressor 4.

[0053] In this example, the refrigerant to be used is R410A, which has a boiling point of 11 degrees Celsius at a pressure of 10 bar.

[0054] Initially, compressor 4 will output the refrigerant, with a pressure of 26 bar and a temperature of 66 degrees Celsius. This refrigerant will enter condenser 3, which will cool down the gaseous refrigerant to a liquid refrigerant, at a pressure of 25.7 bar and a temperature of 33 degrees Celsius.

[0055] The liquid refrigerant will enter expansion valve K1, where it will be expanded into a gas/liquid mixture having a pressure of 8 bar and a temperature of 5 degrees Celsius. Inside evaporator 1, the refrigerant will be heated by airflow A1 which initially is at 25 degrees Celsius. For example, the refrigerant will evaporate inside evaporator 1 into a gaseous state at a pressure of 8 bar and a temperature of 8 degrees Celsius. This gaseous refrigerant will be outputted to compressor 4.

[0056] At the output of evaporator 1, the pressure of the refrigerant is 8 bar. The boiling point of the refrigerant at this pressure equals 8 degrees Celsius. The temperature sensed by sensing unit 9 is 13 degrees Celsius. Consequently, the refrigerant is superheated by 5 degrees Celsius, thereby preventing liquid refrigerant from entering and damaging compressor 4.

[0057] The air outputted by climate control unit 10 has been cooled down to 13 degrees Celsius. Accordingly, the room will gradually cool down. This will result in a decreasing temperature difference between the air in air flow A1 and the refrigerant in evaporator 1. Less heat will therefore be absorbed by the refrigerant in evaporator 1 resulting in a decrease in the amount of superheat.

[0058] Once the desired temperature has been reached, controller 8 may operate climate control unit 10 in a dehumidifying mode. To make this determination, the desired room temperature may be checked against the temperature of the incoming air flow as measured by sensing unit 13. However, additionally or alternatively, the temperature of the outgoing air flow as measured by sensing unit 11 can be used.

[0059] In this mode, the room temperature should be kept substantially constant while decreasing the air humidity. Here it is noted that, during the cooling mode, the humidity has already been reduced from approximately 70 percent to 55 percent, which is still higher than the desired humidity of 40 percent.

[0060] In this mode, a comparison can be made between the temperature of the outgoing air flow as measured by sensing unit 11 and the desired temperature. If this difference is too large, i.e. the temperature of the outgoing air flow is less than the desired temperature minus a given offset, it may be decided by controller 8 that expansion valve K1 should be closed. In such case. all of the refrigerant used in evaporator 1, has also been used by reheat coil 2 for heating up the outgoing air. In this manner, the temperature of the outgoing air can be brought back to within a predefined range of the desired temperature.

[0061] For example, the temperature of the air that has passed through evaporator 1 may be 18 degrees Celsius, whereas the outgoing air may have a temperature of 28 degrees Celsius. Moreover, the pressure and temperature of the liquid refrigerant inside condenser 2 and evaporator 1 may be 42 degrees at 26 bar and 7 degrees at 9 bar, respectively.

[0062] If the temperature is within the predefined range, controller 8 may control both expansion valves K1 and K2. Increasing the orifice of expansion device K1 while decreasing the orifice of K2 ensures that less refrigerant flows through the reheat coil.

[0063] Controller 8 will control expansion valves K1 and K2 such that the desired temperature and humidity is reached while at the same time ensuring that the superheat is maintained within acceptable limits. In this respect, the total flow of refrigerant through expansion devices K1 and K2 is also important. For example, if too much liquid refrigerant is provided to evaporator 1, regardless whether it comes from K1 or K2, the amount of superheat may decrease. To make sure that there is always a positive superheat, one of the expansion devices K1 or K2 is closed before the other is opened.

[0064] In addition, ventilator or fan 5A may be controlled by controller 8 to regulate the heat exchange between evaporator 1 and the incoming air and between reheat coil 2 and the air that has been cooled by evaporator 1. In general, increasing the air flow will also increase the amount of heat that is exchanged.

[0065] Similarly, controller 8 may control ventilator or fan 5B to regulate the amount of heat exchanged between condenser 3 and the outside air. Increasing the air flow using ventilator 5B will increase the amount of heat that is exchanged and will consequently lower the temperature and pressure of the refrigerant leaving condenser 3.

[0066] The skilled person will realize that the abovementioned embodiments are merely. exemplary. Various modifications can be made to the embodiments without departing from the scope of the invention which is defined by the appended claims.