Patent Publication Number: US-2017363334-A1

Title: Vapor compression refrigerant system with secondary modulating heat transfer

Description:
BACKGROUND OF THE INVENTION 
     Field of the Invention 
     This invention is directed toward a vapor compression refrigerant system with secondary, modulating, heat transfer used to control the environment in an enclosed space. 
     Background Art 
     The invention is particularly directed toward a vapor compression refrigerant system to control the environment in an indoor swimming pool. The refrigerant system can control properties of the air in the indoor swimming pool and the temperature of the water in the swimming pool. It is known to control the quality of the air in an indoor swimming pool using a refrigerant circuit circulating a refrigerant. The refrigerant normally used is a phase change refrigerant. It is also known to use the refrigerant to heat the pool water. 
     The use of vapor compression refrigerant systems using phase change refrigerants is costly. The refrigerant is itself costly. The piping system required is costly and maintenance of the piping system is intensive, adding to the cost. There is the possibility that the refrigerant, or oil from a compressor used with the refrigerant, can leak into the swimming pool water, contaminating the water. The cost further increases due to construction and testing normally required at the site. Control of the system is difficult due to the off-on controls employed. 
     SUMMARY OF THE INVENTION 
     It is the purpose of the present invention to provide a vapor compression, refrigerant system to control the environment in an enclosed space, such as an indoor swimming pool, which system is cheaper to build, cheaper to maintain, and cheaper to operate than known systems. It is a further purpose of the present invention to provide a vapor compression, refrigerant system which provides better control of the operation of the system and thus better control of the properties of the air in the system and the temperature of the water in the system. 
     The vapor compression refrigerant system of the present invention employs a simple air dehumidifying system to treat the air from an enclosed space and a heat transfer system to eliminate heat taken out of the air by the air dehumidifying system. The air dehumidifying system employs a phase change refrigerant and is connected to the heat transfer system by a vapor/fluid heat exchanger. The heat transfer system employs a fluid with a low freezing temperature, such as glycol. The heat transfer system has heat removal means to remove heat from the system, Proportional control valves are provided in the heat transfer system to direct precise amounts of the heated fluid to selected ones of the heat removal means as needed. At least one of the heat removal means can provide heat for use in the enclosed space. 
     The present invention minimizes the use of costly phase change refrigerant in the system. The system can result in up to 90% less refrigerant being used in the system. With substantially less refrigerant being used, the piping for the system is simplified. The system can be more easily assembled and tested in a factory before shipment. The system allows the treatment of pool water without the risk of contaminating the water with refrigerant or oil. 
    
    
     
       DESCRIPTION OF THE DRAWING FIG.  1   
         FIG. 1  shows the layout of the system. 
     
    
    
     DESCRIPTION OF PREFERRED EMBODIMENT 
     The vapor compression refrigerant system  1  shown in  FIG. 1  has a dehumidifying system  3 , for treating air from an enclosed space  5  where evaporation occurs, such as an indoor swimming pool. The vapor compression refrigerant system  1  also has a heat transfer system  7  for removing heat from the dehumidifying system  3 . 
     The dehumidifying system  3  has an air circulating system  9  for transporting air from the indoor swimming pool  5  through a pool air inlet duct  11 , into one end  13  of a main air duct  15  and passing through the main air duct  15  to its other end  17  and back to the swimming pool  5  via a pool air outlet duct  19 . A fan  21  at the other end  17  of the main air duct  13  circulates the air through the air circulating system  9 . The air circulating system  9  includes an outside air inlet duct  23  located between the pool air inlet and outlet ducts  11 ,  19  for adding outside air to the circulating air in the main air duct  15  if required. 
     The dehumidifying system  3  has a refrigerant circuit  27  comprising a compressor  29 , a heat exchanger  31 , an expansion valve  33 , and an evaporator  35  connected in series in a loop with a refrigerant line  37 . The evaporator  35  and the expansion valve  33  are located in the main air duct  13  of the air circulating system  9 , between the outside air inlet duct  23  and the pool air inlet duct  11 , to condition the air passing through the main air duct  13 . The refrigerant circuit  27  carries a phase change refrigerant. The evaporator  35  is in the path of the returning pool air in the main air duct  13  that has entered from the pool air inlet duct  11 . The evaporator  35  can remove heat and can condense moisture from the return pool air to condition the air. 
     The vapor compression refrigerant system  1  includes a heat transfer system  7  operating with a normally non-freezing fluid such as glycol. The fluid used would not freeze below the ambient temperature. The heat transfer system  7  is connected to the refrigerant circuit  27  with the heat exchanger  31 . The heat exchanger  31  is a refrigerant/fluid heat exchanger. The heat transfer system  7  picks up heat from the refrigerant circuit  27  in the heat exchanger  31 . 
     The heat transfer system  7  has a feed line  41  leading from the heat exchanger  31  to a heat removal unit  43 , such as an outside air preheat coil  51 , if needed, which can be mounted in the outside air duct  23 . The preheat coil  51  uses the heated fluid to selectively heat outside air entering the main air duct  17  when required. The heat transfer system  7  includes a return line  53  returning the fluid from the preheat coil  51  to the heat exchanger  31 . A valve  55  in the return line  53  controls the flow of the fluid through the preheat coil  51 . A pump  57  is provided in the return line  53 , before the heat exchanger  31 , to circulate the fluid through the heat transfer system  7 . 
     The heat transfer system  7  can have a second heat removal unit  43   a , if needed, in the form of a reheat coil  59  which can be mounted in parallel with the preheat coil  51  between the feed line  41  and the return line  53  of the heat transfer system  7 . A branch feed line  41   a  connects feed line  41  to the reheat coil  59  and a branch return line  53   a  connects the reheat coil  59  to the return line  53 . The reheat coil  59  is mounted in the main air duct  17  just past where the outside air duct  23  joins the main air duct  17  and is used to selectively reheat the return air from the pool area and/or the added outside air if needed. 
     The heat transfer system  7  can have a third heat removal unit  43   b  in the form of a fluid cooler  65  mounted outside the main air duct  15  of the air circulating system  3 . The fluid cooler  65  is connected between the feed and return lines  41 ,  53   a  with branch lines  41   b ,  53   b . The fluid cooler  65  acts as a heat exchanger between the heated fluid and outside air drawn through the cooler. The fluid cooler  65  is connected to the return branch line  53   b  with a first three way modulating mixing valve  67 . The mixing valve  67  can be used to proportion flow of the fluid between the fluid cooler  65  and the reheat coil  59  if needed. 
     The fluid cooler  65  can be replaced with: a fluid to fluid heat exchanger to reject heat to an external heat rejection system. The fluid to fluid heat exchanger can also be used for a heat pump heating mode whenever the compressor is not running during winter, absorbing heat from the external loop. 
     A fourth heat removal means  43   c  in the form of a pool water heater  69  can be used in the heat transfer system  7 . The pool water heater  69  is connected between the feed and return lines  41 ,  53  of the heat transfer circuit  7  with branch lines  41   c ,  53   c  just after the branch return line  53   b  and before the pump  57 . Branch return line  53   c  is connected to the return line  53  with a second three way modulating mixing valve  71 . The second mixing valve  71  can be used to proportion flow of the fluid between the pool water heater  69  and the fluid cooler  65  and/or the reheat coil  59  to maintain the refrigerant head pressure set point in the refrigerant circuit  27 . 
     While the system  1  has been described with four different heat removal means it can be employed with any single one of the heat removal means or with any other combination thereof. A preferred combination of the heat removal means would involve using the reheat coil  59 , the fluid cooler  65  and the pool water heater  69  to dissipate the heat extracted from the refrigerant circuit  27  of the dehumidifying system  3 . The two modulating mixing valves  67 ,  71  would direct the required amount of heat to the reheat coil and the pool water heater. Any excess heat would be disposed of through the fluid cooler, if required. 
     The system  1  allows infinite control of the air temperature and humidity and of the water temperature. Surges of power and temperature due to the start and stop of the compressor  29  and the pump  57  in the refrigerant circuit  27  and the normal fluctuations of temperature in the refrigerant in the refrigerant circuit are eliminated by the use of the modulating heat transfer circuit  7 .