Abstract:
A Cold Plate Refrigeration System Optimized for Energy Efficiency is provided utilizing two refrigerant compressors and a single set of cold plates; or two refrigerant compressors, a conventional evaporator to air heat exchanger, and a single set of cold plates; or a single refrigerant compressor, a conventional evaporator to air heat exchanger, and a single set of cold plates. It is emphasized that this abstract is provided to comply with the rules requiring an abstract that will allow a searcher or other reader to quickly ascertain the subject matter of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. 37 CFR 1.72(b).

Description:
REFERENCE TO A RELATED APPLICATION AND PRIORITY CLAIM  
       [0001]     This application is a continuation-in-part, and claims priority, of pending application Ser. No. 11/372,506 filed 10 Mar. 2006. 
     
    
     BACKGROUND  
       [0002]     Commercial motor vehicles such as medium or heavy duty trucks at times are used to carry perishable items such as foods, and are often provided with insulated truck bodies for this purpose. Various methods are used to refrigerate the interior of the insulated truck body, such as using the vehicle prime mover engine to drive a refrigerant compressor, or by use of a separately powered refrigeration unit. Often, the separately powered refrigeration unit type systems incorporate a small auxiliary diesel engine for autonomous operation, and an electric motor for use when at a loading and unloading location where municipal electric power is available. Actual cooling of the interior of the insulated truck body is accomplished by means of a conventional evaporator to air heat exchanger. The principal disadvantage of this type of system is the inefficiency associated with the weight and fuel consumption of the auxiliary diesel engine, as well as the expense associated with the purchase and installation of the autonomous system and supporting subsystems, including emissions controls. Furthermore, separately powered refrigeration unit systems have undesirable failure mechanisms and maintenance requirements differing from the truck maintenance cycle.  
         [0003]     Vehicles having refrigerant “split systems” where the compressor is engine mounted are cost efficient when compared with systems using small diesel engines. However, since the compressors are engine mounted, capacity limitations exist due to size limitations, system installations are complex, and similar failure mechanisms exist. These systems also require continuous engine operation, which has significant disadvantages relative to fuel costs and anticipated idle reduction requirements.  
         [0004]     One of the more efficient methods of refrigerating an insulated truck body and thereby keeping perishable items fresh is by use of “Cold Plate” technology. “Cold Plate” refrigeration relies upon aluminum or other metal containers called cold plates that are filled with a solution having a pre-determined freezing point, often corresponding to the eutectic point of the given solution. Common solutions utilized include salt brine or anti-freeze and water. Prior to vehicle operation, typically overnight, a small (typically 1.5 horsepower or 1500 watts) on-board refrigerant compressor is operated in conjunction with a condensor, expansion valve, and evaporator heat exchanger to bring the cold plates to a frozen condition. The vehicle then typically departs in the morning for its delivery rounds. The refrigerated cargo is maintained at a proper temperature by the latent heat of fusion that is absorbed until the cold plate solution thaws.  
         [0005]     Cold plate refrigeration is very reliable, energy and cost efficient due to the use of 115 Volts Alternating Current (VAC) single phase, 230 VAC three phase, or similar utility electricity. It is also capable of maintaining relatively precise temperature when compared to separately powered refrigeration unit type systems or split systems. The provision of relatively precise temperatures is of particular advantage in the delivery of milk or other temperature sensitive foods being subject to strict FDA guidelines. The major limitation of the Cold Plate refrigeration system is the usable operational time. The available time for deliveries before the cold plate solution thaws typically limits vehicle usage to a single shift operation, though the usable time may be extended by opportunistic plug-in and operation of the on-board refrigeration compressor at points of delivery.  
       SUMMARY  
       [0006]     The Cold Plate Refrigeration System Optimized for Energy Efficiency described herein provides several optimized solutions for vehicle insulated truck body cold plate refrigeration systems. These solutions include providing an on-board system comprised of two refrigerant compressors and a single set of cold plates; or two refrigerant compressors, a conventional evaporator to air heat exchanger, and a single set of cold plates; or a single refrigerant compressor, a conventional evaporator to air heat exchanger, and a single set of cold plates.  
         [0007]     One refrigerant compressor may function and be sized to achieve rapid cooling of the liquid medium in the cold plates using utility Alternating Current (AC) electrical power when the vehicle is plugged-in, or when a generator driven by the vehicle engine and having an inverter has sufficient available power to operate it. A second refrigerant compressor may be sized to approximately maintain the eutectic medium at or below its frozen state under various environmental operating conditions, or to simply operate a conventional evaporator to air heat exchanger for supplemental cooling, when the vehicle engine is providing the power to operate the system. Operation of the second compressor may be continuous while the vehicle is in operation, or it may be equipped to sense the state of the cold plates&#39; eutectic solution, such that it only operates once the solution has thawed. The second compressor may even be based on a hysteresis range of interior temperature of the insulated truck body, rather than upon the condition of the cold plates. The two refrigerant compressors may also be of approximately the same power rating, and may be used together or separately in certain situations, as will be disclosed herein.  
         [0008]     The refrigerant compressor or compressors are electrically powered, and may receive electrical power from a vehicle primary engine driven generator, which electrical power may be converted by an inverter, or the electrically powered compressor or compressors may receive power from a shore power connection, depending on the circumstances. Selection of a power source and management of the operation of the refrigerant compressors may be accomplished by a switching unit, which switching unit may be manual or automatic. The vehicle primary engine driven generator may produce Direct Current (DC) power in the range of eight to sixteen volts DC, as is common with motor vehicles, or it may produce DC power in a higher range, typically 40 to 350 volts DC. This electrical power may be then converted by an inverter to 115 VAC operating at sixty hertz. In certain embodiments, the electrical power may be converted by the inverter to 230 VAC split-phase or to 208 volts three-phase, or may be converted by the inverter to 115 VAC and then be further converted by a transformer to 230 VAC split-phase or to 208 volts three-phase. The use of higher DC voltage as produced by the vehicle primary engine driven generator in combination with an inverter results in overall greater efficiency, and allows the use of a smaller, less expensive inverter.  
         [0009]     The switching unit may sense when the vehicle primary engine is idling, or is in a condition of producing less power due to a de-rate imposed by environmental conditions, and may respond by selecting operation of only one compressor or directing the refrigerating capacity to only one of the cold plates or interior evaporator. The switching unit may further be capable of sensing and responding to other factors, such as frosting of the interior evaporator or cold plates, or failure of a compressor or circuitry. It may also control one or more valves directing the output of the refrigerant compressor or compressors.  
         [0010]     As described above, the Cold Plate Refrigeration System Optimized for Energy Efficiency and a vehicle made with this system provide a number of advantages, some of which have been described above and others of which are inherent in the invention. Also, modifications may be proposed to the Cold Plate Refrigeration System Optimized for Energy Efficiency or a vehicle made with the system without departing from the teachings herein. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]      FIG. 1 —A vehicle having an insulated truck body.  
         [0012]      FIG. 2 —A vehicle having an insulated truck body, an engine, a generator, an inverter, shore power, a switching unit, refrigerant compressors, a condenser, cold plates, and an interior evaporator.  
         [0013]      FIG. 3 —A first embodiment of the invention.  
         [0014]      FIG. 4 —A second embodiment of the invention.  
         [0015]      FIG. 5 —A third embodiment of the invention.  
         [0016]      FIG. 6 —A fourth embodiment of the invention.  
         [0017]      FIG. 7 —A fifth embodiment of the invention.  
         [0018]      FIG. 8 —A sixth embodiment of the invention.  
         [0019]      FIG. 9 —A seventh embodiment of the invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0020]      FIG. 1  shows a vehicle  101  having a body  102 , a chassis  103 , and an insulated truck body  104 . The insulated truck body  104  attached to the vehicle  101  shown in  FIG. 1  is provided with a conventional separately powered refrigeration unit  105 .  
         [0021]      FIG. 2  shows a vehicle  101  having a body  102 , a chassis  103 , and an insulated truck body  104 . The vehicle  101  has an engine  106  for propulsion, to which engine  106  is attached a direct current (DC) electrical generator  107 . The DC electrical generator  107  driven by the engine  106  by means of a belt drive  108 , though it is within the scope of the invention that the DC electrical generator  107  may be driven by the engine  106  by other means, such as gears or hydraulic pumps and motors. The DC electricity produced by the DC electrical generator  107  is then conducted to a power converter/inverter  109 , which power converter/inverter  109  serves to convert the DC electricity to alternating current (AC) electricity. As noted previously in this specification, the DC electrical generator  107  may produce DC electricity in the range of eight to sixteen volts DC, or it may produce DC power in a higher range, such as 40 to 350 volts DC. Further, the power converter/inverter  109  may convert the electricity produced by the DC electrical generator  107  to 115 volts AC operating at sixty hertz, to 230 volts AC split-phase, or to 208 volts AC three-phase. The AC electricity is then conducted from the power converter/inverter  109  to a switching unit  112 . The vehicle  101  is also provided with a shore power hookup  111 , which shore power hookup  111  serves to connect the vehicle  101  to municipal utility provided electrical power of 115 volts AC or 230 volts AC. The electricity provided through the shore power hookup  111  is then conducted to the switching unit  112 . The switching unit  112 , in turn, selectively conducts electricity provided by the power converter/inverter  109  or by the shore power hookup  111  to one or both of a first electrically powered refrigerant compressor  115  and a second electrically powered refrigerant compressor  116  if so provided, as will be further illustrated in subsequent figures. The first electrically powered refrigerant compressor  115  and second electrically powered refrigerant compressor  116  if so provided selectively provide refrigerant to evaporators within either or both of cold plates  113  or an interior evaporator unit  120 . As is common with cold plates, the cold plates  113  in  FIG. 2  are provided with recirculating fans  114 . As is also common with vehicles having refrigeration systems, the vehicle  101  in  FIG. 2  is provided with a condenser  118  having at least one condenser fan  119 .  
         [0022]      FIG. 3  shows a vehicle  101  having a body  102 , a chassis  103  (not visible in  FIG. 3 ), and an insulated truck body  104 , similar to the vehicle  101  in  FIG. 2 . The vehicle  101  again has an engine  106  for propulsion and a direct current (DC) electrical generator  107  driven by means of a belt drive  108 . The DC electricity, whether eight to sixteen volts DC or 40 to 350 volts DC, produced by the DC electrical generator  107  is again converted by a power converter/inverter  109  to 115 volt alternating current (AC) electricity, to 230 volts AC split-phase, or to 208 volts AC three-phase. The AC electricity is then conducted from the power converter/inverter  109  to a switching unit  112 . The vehicle  101  is again provided with a shore power hookup  111 , which shore power hookup  111  serves to connect the vehicle  101  to municipal utility provided electrical power of 115 volts AC or 230 volts AC. The electricity provided through the shore power hookup  111  is conducted to a junction  125 , and from the junction  125  both to the switching unit  112  and directly to the first electrically powered refrigerant compressor  115 . The switching unit  112 , in turn, selectively conducts electricity provided by the power converter/inverter  109  or by the shore power hookup  111  to the second electrically powered refrigerant compressor  116 . When the vehicle  101  is plugged in, cooling is provided by the first electrically powered refrigerant compressor  115 , and selectively by the second electrically powered refrigerant compressor  116 , as determined by the switching unit  112 . When electricity is being provided only by the power converter/inverter  109  then cooling is provided only by the second electrically powered refrigerant compressor  116 . If the vehicle  101  is both plugged in and running, then cooling may be provided by the first electrically powered refrigerant compressor  115  by means of electricity provided by the shore power hookup  111 , and cooling may at the same time be provided by the second electrically powered refrigerant compressor  116  by means of electricity provided by the power converter/inverter  109 . Similar to the vehicle  101  shown in  FIG. 2 , the vehicle shown in  FIG. 3  is provided with cold plates  113  located within the insulated truck body  104 . The electrically powered refrigerant compressors  115  and  116  operate to pressurize a refrigerant loop  117 , which refrigerant loop is provided with a condenser  118 , an expansion valve  121 , and an evaporator  126  within the cold plates  113 . The electrically powered refrigerant compressors  115  and  116  may be of approximately the same size of about one horsepower capacity, or the second electrically powered refrigerant compressor  116  may be of a size of about one horsepower capacity and the first electrically powered refrigerant compressor  115  may be of a size of about two horsepower capacity. For the sake of illustration, the refrigerant loop  117  is shown as double lines from the electrically powered refrigerant compressors  115  and  116  to the condenser  118 , single line from the condenser  118  to the expansion valve  121 , single line from the expansion valve  121  to the evaporator  126 , and double lines from the evaporator  126  to the electrically powered refrigerant compressors  115  and  116 . However, it is within the scope of the invention that the lines be any combination of double and single between these devices, and that there may be single condenser  118  or double condensers, or that there may be a single expansion valve  121  or double expansion valves, or that there may be a single evaporator  126  within the cold plates  113  or double evaporators within the cold plates  113 . A thermostat  122  and a frost sensor  123  are attached to the cold plates  113 , and communicate with the switching unit  112 . As is common with cold plates, the cold plates  113  in  FIG. 3  are again provided with recirculating fans  114 . The condenser  118  is also provided with at least one condenser fan  119 .  
         [0023]      FIG. 4  again shows a vehicle  101  having a body  102 , a chassis  103  (not visible in  FIG. 4 ), an insulated truck body  104 , an engine  106  for propulsion, and a direct current (DC) electrical generator  107  driven by means of a belt drive  108 . The eight to sixteen volts DC or 40 to 350 volts DC produced by the DC electrical generator  107  is again converted by a power converter/inverter  109  to 115 volt alternating current (AC) electricity, to 230 volts AC split-phase, or to 208 volts AC three-phase, which is then conducted from the power converter/inverter  109  to a switching unit  112 . The vehicle  101  is again provided with a shore power hookup  111 , which shore power hookup  111  serves to connect the vehicle  101  to municipal utility provided electrical power of 115 volts AC or 230 volts AC. The electricity provided through the shore power hookup  111  is also conducted to the switching unit  112 . The switching unit  112 , in turn, selectively conducts electricity provided by the power converter/inverter  109  or by the shore power hookup  111  to the first electrically powered refrigerant compressor  115  and/or the second electrically powered refrigerant compressor  116 . When the vehicle  101  is plugged in, cooling may be provided by the first electrically powered refrigerant compressor  115 , the second electrically powered refrigerant compressor  116 , or both, as determined by the switching unit  112 . When electricity is being provided only by the power converter/inverter  109  then cooling may be provided by the first electrically powered refrigerant compressor  115  and the second electrically powered refrigerant compressor  116 , or by the second electrically powered refrigerant compressor  116  only. The switching unit  112  may be capable of sensing the status of the vehicle engine  106  and electrical system, such that if the vehicle engine  106  and DC electrical generator  107  is generating sufficient extra power, both first electrically powered refrigerant compressor  115  and second electrically powered refrigerant compressor  116  are provided with power. If the vehicle engine is in a de-rate condition or at idle, or if the vehicle electrical system is consuming an excess of electricity, then the switching unit  112  may only provide power to the second electrically powered refrigerant compressor  116 . If the vehicle  101  is both plugged in and running, then cooling may be provided by the first electrically powered refrigerant compressor  115  by means of electricity provided by the shore power hookup  111 , and cooling may at the same time be provided by the second electrically powered refrigerant compressor  116  by means of electricity provided by the power converter/inverter  109 . The vehicle shown in  FIG. 4  is again provided with cold plates  113  located within the insulated truck body  104 . The refrigerant electrically powered refrigerant compressors  115  and  116  operate to pressurize the refrigerant loop  117 , which refrigerant loop is provided with a condenser  118 , an expansion valve  121 , and an evaporator  126  within the cold plates  113 . The electrically powered refrigerant compressors  115  and  116  may be of approximately the same size of about one horsepower capacity, or the second electrically powered refrigerant compressor  116  may be of a size of about one horsepower capacity and the first electrically powered refrigerant compressor  115  may be of a size of about two horsepower capacity. For the sake of illustration, the refrigerant loop  117  is shown as double lines from the electrically powered refrigerant compressors  115  and  116  to the condenser  118 , single line from the condenser  118  to the expansion valve  121 , single line from the expansion valve  121  to the evaporator  126 , and double lines from the evaporator  126  to the electrically powered refrigerant compressors  115  and  116 . However, it is within the scope of the invention that the lines be any combination of double and single between these devices, and that there may be single condenser  118  or double condensers, or that there may be a single expansion valve  121  or double expansion valves, or that there may be a single evaporator  126  within the cold plates  113  or double evaporators within the cold plates. A thermostat  122  and a frost sensor  123  are attached to the cold plates  113 , and communicate with the switching unit  112 . The cold plates  113  in  FIG. 4  are again provided with recirculating fans  114 , and the condenser  118  is also provided with at least one condenser fan  119 .  
         [0024]      FIG. 5  again shows a vehicle  101  having a body  102 , a chassis  103  (not visible in  FIG. 5 ), an insulated truck body  104 , an engine  106  for propulsion, and a direct current (DC) electrical generator  107  driven by means of a belt drive  108 . The eight to sixteen volts DC or 40 to 350 volts DC produced by the DC electrical generator  107  is again converted by a power converter/inverter  109  to 115 volt alternating current (AC) electricity, to 230 volts AC split-phase, or to 208 volts AC three-phase, which is then conducted from the power converter/inverter  109  to a switching unit  112 . The vehicle  101  is again provided with a shore power hookup  111 , which shore power hookup  111  serves to connect the vehicle  101  to municipal utility provided electrical power of 115 volts AC or 230 volts AC. The electricity provided through the shore power hookup  111  is also conducted to the switching unit  112 . The switching unit  112 , in turn, selectively conducts electricity provided by the power converter/inverter  109  or by the shore power hookup  111  to the first electrically powered refrigerant compressor  115 , the second electrically powered refrigerant compressor  116 , or both. The vehicle shown in  FIG. 5  is not only provided with cold plates  113  located within the insulated truck body  104 , but also an interior evaporator unit  120 . The electrically powered refrigerant compressors  115  and  116  operate to pressurize two refrigerant loops  117 , such that refrigerant provided by the first electrically powered refrigerant compressor  115  serves to supply the evaporator  126  within the cold plates  113 , and the refrigerant provided by the second electrically powered refrigerant compressor  116  serves to supply the interior evaporator unit  120 . Both refrigerant loops  117  are provided with condensers  118  (shown in a common housing) and expansion valves  121 . When the vehicle  101  is plugged in, cooling may be provided by the first electrically powered refrigerant compressor  115  through the evaporator  126  within the cold plates  113 , the second electrically powered refrigerant compressor  116  through the interior evaporator unit  120 , or both, as determined by the switching unit  112 . When electricity is being provided only by the power converter/inverter  109  then cooling may be provided by the first electrically powered refrigerant compressor  115  through the evaporator  126  within the cold plates  113  and the second electrically powered refrigerant compressor  116  through the interior evaporator unit  120 , or by the second electrically powered refrigerant compressor  116  through the interior evaporator unit  120  only. The switching unit  112  may be capable of sensing the status of the vehicle engine  106  and electrical system, such that if the vehicle engine  106  and DC electrical generator  107  is generating sufficient extra power, both first electrically powered refrigerant compressor  115  and second electrically powered refrigerant compressor  116  are provided with power. If the vehicle engine is in a de-rate condition or at idle, or if the vehicle electrical system is consuming an excess of electricity, then the switching unit  112  may only provide power to the second electrically powered refrigerant compressor  116 . If the vehicle  101  is both plugged in and running, then cooling may be provided by the first electrically powered refrigerant compressor  115  through the evaporator  126  within the cold plates  113  by means of electricity provided by the shore power hookup  111 , and cooling may at the same time be provided by the second electrically powered refrigerant compressor  116  through the interior evaporator unit  120  by means of electricity provided by the power converter/inverter  109 . The electrically powered refrigerant compressors  115  and  116  may be of approximately the same size of about one horsepower capacity, or the second electrically powered refrigerant compressor  116  may be of a size of about one horsepower capacity and the first electrically powered refrigerant compressor  115  may be of a size of about two horsepower capacity. A thermostat  122  and a frost sensor  123  are attached to the cold plates  113 , and communicate with the switching unit  112 . Another thermostat  122  and frost sensor  123  are attached to the interior evaporator unit  120 , and also communicate with the switching unit  112  (for clarity of illustration, the wires connecting the thermostat  122  and the frost sensor  123  of the interior evaporator unit  120  to the switching unit  112  are not shown.) The cold plates  113  in  FIG. 5  are again provided with recirculating fans  114 , the condenser  118  is provided with at least one condenser fan  119 , and the interior evaporator unit  120  is provided with at least one interior evaporator fan  127 .  
         [0025]      FIG. 6  again shows a vehicle  101  having a body  102 , a chassis  103  (not visible in  FIG. 6 ), an insulated truck body  104 , an engine  106  for propulsion, and a direct current (DC) electrical generator  107  driven by means of a belt drive  108 . The eight to sixteen volts DC or 40 to 350 volts DC produced by the DC electrical generator  107  is again converted by a power converter/inverter  109  to 115 volt alternating current (AC) electricity, to 230 volts AC split-phase, or to 208 volts AC three-phase, which is then conducted from the power converter/inverter  109  to a switching unit  112 . The vehicle  101  is again provided with a shore power hookup  111 , which shore power hookup  111  serves to connect the vehicle  101  to municipal utility provided electrical power of 115 volts AC or 230 volts AC. The electricity provided through the shore power hookup  111  is also conducted to the switching unit  112 . The switching unit  112 , in turn, selectively conducts electricity provided by the power converter/inverter  109  or by the shore power hookup  111  to the first electrically powered refrigerant compressor  115 , the second electrically powered refrigerant compressor  116 , or both. The vehicle shown in  FIG. 6  is provided with cold plates  113  located within the insulated truck body  104  and an interior evaporator unit  120 . The electrically powered refrigerant compressors  115  and  116  operate to pressurize two refrigerant loops  117 , similar to the two refrigerant loops shown in  FIG. 5 , such that refrigerant provided by the first electrically powered refrigerant compressor  115  in  FIG. 6  serves to supply the evaporator  126  within the cold plates  113 , and the refrigerant provided by the second electrically powered refrigerant compressor  116  in  FIG. 6  generally serves to supply the interior evaporator unit  120 . Additionally the refrigerant loop  117  pressurized by the second electrically powered refrigerant compressor  116  is further provided with a refrigerant control valve  124 , which serves to selectively direct the refrigerant provided by the second electrically powered refrigerant compressor  116  to either the interior evaporator unit  120  or the evaporator  126  within the cold plates  113 . The refrigerant control valve  124  is controlled by the switching unit  112  (for clarity of illustration, the wires connecting the refrigerant control valve  124  to the switching unit  112  are not shown). Both refrigerant loops  117  are provided with condensers  118  (shown in a common housing) and expansion valves  121 . When the vehicle  101  is plugged in, cooling may be provided by the first electrically powered refrigerant compressor  115  through the evaporator  126  within the cold plates  113 , the second electrically powered refrigerant compressor  116  through the interior evaporator unit  120 , or both, or by the first electrically powered refrigerant compressor  115  through the evaporator  126  within the cold plates  113  and by the second electrically powered refrigerant compressor  116  through the evaporator  126  within the cold plates  113  by means of operation of the refrigerant control valve  124 , as determined by the switching unit  112 . When electricity is being provided only by the power converter/inverter  109  then cooling may be provided by the first electrically powered refrigerant compressor  115  through the evaporator  126  within the cold plates  113  and the second electrically powered refrigerant compressor  116  through the interior evaporator unit  120 , by the second electrically powered refrigerant compressor  116  through the interior evaporator unit  120  only, or by the second electrically powered refrigerant compressor  116  through the evaporator  126  within the cold plates  113  by means of operation of the refrigerant control valve  124 , as determined by the switching unit  112 . The switching unit  112  may be capable of sensing the status of the vehicle engine  106  and electrical system, such that if the vehicle engine  106  and DC electrical generator  107  is generating sufficient extra power, both first electrically powered refrigerant compressor  115  and second electrically powered refrigerant compressor  116  are provided with power. If the vehicle engine is in a de-rate condition or at idle, or if the vehicle electrical system is consuming an excess of electricity, then the switching unit  112  may only provide power to the second electrically powered refrigerant compressor  116 . If the vehicle  101  is both plugged in and running, then cooling may be provided by the first electrically powered refrigerant compressor  115  through the evaporator  126  within the cold plates  113  by means of electricity provided by the shore power hookup  111 , and cooling may at the same time be provided by the second electrically powered refrigerant compressor  116  through the interior evaporator unit  120 , or through the evaporator  126  within the cold plates  113 , by means of electricity provided by the power converter/inverter  109 . The electrically powered refrigerant compressors  115  and  116  may be of approximately the same size of about one horsepower capacity, or the second electrically powered refrigerant compressor  116  may be of a size of about one horsepower capacity and the first electrically powered refrigerant compressor  115  may be of a size of about two horsepower capacity. A thermostat  122  and a frost sensor  123  are attached to the cold plates  113 , and communicate with the switching unit  112 . Another thermostat  122  and frost sensor  123  are attached to the interior evaporator unit  120 , and also communicate with the switching unit  112  (for clarity of illustration, the wires connecting the thermostat  122  and the frost sensor  123  of the interior evaporator unit  120  to the switching unit  112  are not shown.) The cold plates  113  in  FIG. 6  are again provided with recirculating fans  114 , the condenser  118  is provided with at least one condenser fan  119 , and the interior evaporator unit  120  is provided with at least one interior evaporator fan  127 .  
         [0026]      FIG. 7  again shows a vehicle  101  having a body  102 , a chassis  103  (not visible in  FIG. 7 ), an insulated truck body  104 , an engine  106  for propulsion, and a direct current (DC) electrical generator  107  driven by means of a belt drive  108 . The eight to sixteen volts DC or 40 to 350 volts DC produced by the DC electrical generator  107  is again converted by a power converter/inverter  109  to 115 volt alternating current (AC) electricity, to 230 volts AC split-phase, or to 208 volts AC three-phase, which is then conducted from the power converter/inverter  109  to a controller  129  of the second electrically powered refrigerant compressor  116 . The vehicle  101  is again provided with a shore power hookup  111 , which shore power hookup  111  serves to connect the vehicle  101  to municipal utility provided electrical power of 115 volts AC or 230 volts AC. The electricity provided through the shore power hookup  111  is conducted to a controller  128  of the first electrically powered refrigerant compressor  115 . The controller  128  and the controller  129  are in signal communication with one another. The vehicle shown in  FIG. 7  is provided with cold plates  113  located within the insulated truck body  104 , and an interior evaporator unit  120 . The electrically powered refrigerant compressors  115  and  116  operate to pressurize two refrigerant loops  117 , such that refrigerant provided by the first electrically powered refrigerant compressor  115  serves to supply the evaporator  126  within the cold plates  113 , and the refrigerant provided by the second electrically powered refrigerant compressor  116  serves to supply the interior evaporator unit  120 . Both refrigerant loops  117  are provided with condensers  118  (shown in a common housing) and expansion valves  121 . When the vehicle  101  is plugged in, cooling is provided by the first electrically powered refrigerant compressor  115  through the evaporator  126  within the cold plates  113 . When electricity is being provided only by the power converter/inverter  109  then cooling is provided by the second electrically powered refrigerant compressor  116  through the interior evaporator unit  120  only. If the vehicle  101  is both plugged in and running, then cooling may be provided by the first electrically powered refrigerant compressor  115  through the evaporator  126  within the cold plates  113  by means of electricity provided by the shore power hookup  111 , and cooling may at the same time be provided by the second electrically powered refrigerant compressor  116  through the interior evaporator unit  120  by means of electricity provided by the power converter/inverter  109 . Alternately, by means of communication between the controller  128  for the first electrically powered refrigerant compressor  115  and the controller  129  for the second compressor, the first electrically powered refrigerant compressor  115  may provide cooling through the evaporator  126  within the cold plates  113 , while allowing the second electrically powered refrigerant compressor  116  to be at rest, thereby relieving the DC electrical generator  107  to provide electricity for other needs of the vehicle  101 , such as charging the vehicle battery (not shown). A thermostat  122  and a frost sensor  123  are attached to the cold plates  113 , and communicate with the controller  128  for the first electrically powered refrigerant compressor  115 . Another thermostat  122  and frost sensor  123  are attached to the interior evaporator unit  120 , and communicate with the controller  129  for the second electrically powered refrigerant compressor  116 . If the vehicle  101  is both plugged in and running, the controller  128  and the controller  129  may determine whether the first electrically powered refrigerant compressor  115  is to provide cooling through the evaporator  126  within the cold plates  113  or the second electrically powered refrigerant compressor  116  is to provide cooling through the interior evaporator unit  120 , based on the temperature or frost conditions of the cold plates  113  or the interior evaporator unit  120 . The electrically powered refrigerant compressors  115  and  116  may be of approximately the same size of about one horsepower capacity, or the second electrically powered refrigerant compressor  116  may be of a size of about one horsepower capacity and the first electrically powered refrigerant compressor  115  may be of a size of about two horsepower capacity. The cold plates  113  in  FIG. 7  are again provided with recirculating fans  114 , the condenser  118  is provided with at least one condenser fan  119 , and the interior evaporator unit  120  is provided with at least one interior evaporator fan  127 .  
         [0027]      FIG. 8  again shows a vehicle  101  having a body  102 , a chassis  103  (not visible in  FIG. 5 ), an insulated truck body  104 , an engine  106  for propulsion, and a direct current (DC) electrical generator  107  driven by means of a belt drive  108 . The eight to sixteen volts DC or 40 to 350 volts DC produced by the DC electrical generator  107  is again converted by a power converter/inverter  109  to 115 volt alternating current (AC) electricity, to 230 volts AC split-phase, or to 208 volts AC three-phase, which is then conducted from the power converter/inverter  109  to a switching unit  112 . The vehicle  101  is again provided with a shore power hookup  111 , which shore power hookup  111  serves to connect the vehicle  101  to municipal utility provided electrical power of 115 volts AC or 230 volts AC. The electricity provided through the shore power hookup  111  is also conducted to the switching unit  112 . The switching unit  112 , in turn, selectively conducts electricity provided by the power converter/inverter  109  or by the shore power hookup  111  to the electrically powered refrigerant compressor  115 . The vehicle shown in  FIG. 8  is provided with cold plates  113  located within the insulated truck body  104 , and an interior evaporator unit  120 . The electrically powered refrigerant compressor  115  operates to pressurize a refrigerant loop  117 , such that refrigerant provided by the electrically powered refrigerant compressor  115  serves to supply the evaporator  126  within the cold plates  113  or the interior evaporator unit  120 , depending upon the position of a refrigerant control valve  124 . The refrigerant control valve  124  is controlled by the switching unit  112  (for clarity of illustration, the wires connecting the refrigerant control valve  124  to the switching unit  112  are not shown). The refrigerant loop  117  is provided with a condenser  118  and an expansion valve  121 . When the vehicle  101  is plugged in, cooling may be provided by the electrically powered refrigerant compressor  115  through the evaporator  126  within the cold plates  113  or through the interior evaporator unit  120 , depending upon the setting of the refrigerant control valve  124  as determined by the switching unit  112 . When electricity is being provided only by the power converter/inverter  109  then cooling may be provided by the electrically powered refrigerant compressor  115  through the evaporator  126  within the cold plates  113  or through the interior evaporator unit  120 , again depending upon the setting of the refrigerant control valve  124  as determined by the switching unit  112 . The switching unit  112  may be capable of sensing the status of the vehicle engine  106  and electrical system, such that if the vehicle engine  106  and DC electrical generator  107  is generating sufficient extra power, the electrically powered refrigerant compressor  115  preferentially provides cooling through the evaporator  126  within the cold plates  113 . If the vehicle engine is in a de-rate condition or at idle, or if the vehicle electrical system is consuming an excess of electricity, then the switching unit  112  may set the refrigerant control valve  124  to allow cooling only by the interior evaporator unit  120 . Additionally, the electrically powered refrigerant compressor  115  may be switchable between one horsepower capacity and two horsepower capacity, such that the switching unit  112  may control the capacity of the electrically powered refrigerant compressor  115 , depending on the conditions of the vehicle engine  106  and DC electrical generator  107 . Additionally, a thermostat  122  and a frost sensor  123  is attached to the cold plates  113 , and communicate with the switching unit  112 . Another thermostat  122  and frost sensor  123  is attached to the interior evaporator unit  120 , and also communicate with the switching unit  112  (for clarity of illustration, the wires connecting the thermostat  122  and the frost sensor  123  of the interior evaporator unit  120  to the switching unit  112  are not shown.) The setting of the electrically powered refrigerant compressor  115  capacity and of the refrigerant control valve  124  may depend upon the temperature and frost conditions of the cold plates  113  and of the interior evaporator unit  120 . The cold plates  113  in  FIG. 8  are again provided with recirculating fans  114 , the condenser  118  is provided with at least one condenser fan  119 , and the interior evaporator unit  120  is provided with at least one interior evaporator fan  127 .  
         [0028]      FIG. 9  again shows a vehicle  101  having a body  102 , a chassis  103  (not visible in  FIG. 5 ), an insulated truck body  104 , an engine  106  for propulsion, and a direct current (DC) electrical generator  107  driven by means of a belt drive  108 . The eight to sixteen volts DC or 40 to 350 volts DC produced by the DC electrical generator  107  is again converted by a power converter/inverter  109  to approximately 115 volts alternating current (AC) electricity, which is then conducted from the power converter/inverter  109  to a transformer  110 . The transformer  110  converts the 115 volt AC electricity to 230 volt AC split-phase electricity or to 208 volts AC three-phase. The 230 volt AC split-phase or 208 volts AC three-phase electricity is then conducted to the switching unit  112 . The vehicle  101  is again provided with a shore power hookup  111 , which shore power hookup  111  serves to connect the vehicle  101  to municipal utility provided electrical power of 230 volts AC. The electricity provided through the shore power hookup  111  is also conducted to the switching unit  112 . The switching unit  112 , in turn, selectively conducts electricity provided by the power converter/inverter  109  or by the shore power hookup  111  to the electrically powered refrigerant compressor  115 . The vehicle shown in  FIG. 9  is again provided with cold plates  113  with an evaporator  126 , an interior evaporator unit  120 , a refrigerant loop  117 , a condenser  118 , an expansion valve  121 , and a refrigerant control valve  124 . The refrigerant control valve  124  is again controlled by the switching unit  112  (for clarity of illustration, the wires connecting the refrigerant control valve  124  to the switching unit  112  are not shown). When the vehicle  101  is plugged in, cooling may be provided by the electrically powered refrigerant compressor  115  through the evaporator  126  within the cold plates  113  or through the interior evaporator unit  120 , depending upon the setting of the refrigerant control valve  124  as determined by the switching unit  112 . When electricity is being provided only by the power converter/inverter  109  through the transformer  110  then cooling may be provided by the electrically powered refrigerant compressor  115  through the evaporator  126  within the cold plates  113  or through the interior evaporator unit  120 , again depending upon the setting of the refrigerant control valve  124  as determined by the switching unit  112 . The switching unit  112  may again be capable of sensing the status of the vehicle engine  106  and electrical system, such that if the vehicle engine  106  and DC electrical generator  107  is generating sufficient extra power, the electrically powered refrigerant compressor  115  preferentially provides cooling through the evaporator  126  within the cold plates  113 . If the vehicle engine is in a de-rate condition or at idle, or if the vehicle electrical system is consuming an excess of electricity, then the switching unit  112  may set the refrigerant control valve  124  to allow cooling only by the interior evaporator unit  120 . As before, the electrically powered refrigerant compressor  115  may be switchable between one horsepower capacity and two horsepower capacity, such that the switching unit  112  may control the capacity of the electrically powered refrigerant compressor  115 , depending on the conditions of the vehicle engine  106  and DC electrical generator  107 . Additionally, a thermostat  122  and a frost sensor  123  is attached to the cold plates  113 , and communicate with the switching unit  112 . Another thermostat  122  and frost sensor  123  is attached to the interior evaporator unit  120 , and also communicate with the switching unit  112  (for clarity of illustration, the wires connecting the thermostat  122  and the frost sensor  123  of the interior evaporator unit  120  to the switching unit  112  are not shown.) The setting of the electrically powered refrigerant compressor  115  capacity and of the refrigerant control valve  124  may depend upon the temperature and frost conditions of the cold plates  113  and of the interior evaporator unit  120 . The cold plates  113  in  FIG. 9  are again provided with recirculating fans  114 , the condenser  118  is provided with at least one condenser fan  119 , and the interior evaporator unit  120  is provided with at least one interior evaporator fan  127 .  
         [0029]     While specific embodiments have been described in detail in the foregoing detailed description and illustrated in the accompanying drawings, those with ordinary skill in the art will appreciate that various permutations of the invention are possible without departing from the teachings disclosed herein. Accordingly, the particular arrangements disclosed are meant to be illustrative only and not limiting as to the scope of the invention, which is to be given the full breadth of the appended claims and any and all equivalents thereof. Other advantages to a vehicle equipped with a Cold Plate Refrigeration System Optimized for Energy Efficiency may also be inherent in the invention, without having been described above.