Electronic temperature control system
First Claim
1. A refrigeration control system for a refrigeration system including a refrigerated display case with a primary air conduit having an air outlet opening and an air inlet opening, an evaporator coil arranged within the primary air conduit for refrigerating air passing through such conduit, and an expansion valve coupled to the inlet end of the evaporator coil, said refrigeration control system comprising:
- a pressure sensing means arranged at the refrigerant discharge line from the evaporator coil for sensing the pressure (P) of the refrigerant within such discharge line;
means for determining the saturation temperature (Tsat) of the refrigerant from the measurement of pressure P;
means for setting a level of superheat (Tsh) desired within the refrigerant discharged from the evaporator coil and setting a desired temperature (T2set) for such discharge refrigerant by
space="preserve" listing-type="equation">T.sub.2set =T.sub.sat +T.sub.s ;
a second temperature sensing means arranged adjacent to the refrigerant discharge line from the evaporator coil for measuring the temperature (T2) of the refrigerant discharged from the evaporator coil;
comparator means for comparing temperature T2 with temperature T2set and providing an output comparison signal if T2 <
T2set ; and
,control means receiving the output comparison signal and providing an output control signal for controlling operation of the refrigeration system for maintaining temperature T2 equal to or above temperature T2set.
9 Assignments
0 Petitions
Accused Products
Abstract
A refrigeration system including a refrigeration control system for controlling the operation of the refrigeration system so as to insure that the temperature of the refrigerant discharged from the evaporator coil is above the saturation temperature. The refrigeration system includes at least one refrigerated display case having an evaporator within the primary air conduit and an expansion valve coupled to the inlet end of the evaporator coil. The control system includes: a pressure sensor arranged within the refrigerant discharge line, i.e. suction line to compressor, from the evaporator coil; a first temperature sensor arranged at the air discharge side of the evaporator coil for sensing the temperature (T1) of the air that has passed over the evaporator coil, a second temperature sensor arranged adjacent to the refrigerant discharge end of the evaporator coil for measuring the temperature (T2) of the refrigerant discharged from the evaporator coil and a third temperature sensor arranged adjacent the inlet end of the evaporator coil for sensing the temperature (T3) of the refrigerant flowing into the evaporator coil. Based upon a comparison of temperatures T1, T2 and T3 a series of output control signals are provided for controlling the operation of the expansion valve.
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Citations
36 Claims
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1. A refrigeration control system for a refrigeration system including a refrigerated display case with a primary air conduit having an air outlet opening and an air inlet opening, an evaporator coil arranged within the primary air conduit for refrigerating air passing through such conduit, and an expansion valve coupled to the inlet end of the evaporator coil, said refrigeration control system comprising:
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a pressure sensing means arranged at the refrigerant discharge line from the evaporator coil for sensing the pressure (P) of the refrigerant within such discharge line; means for determining the saturation temperature (Tsat) of the refrigerant from the measurement of pressure P; means for setting a level of superheat (Tsh) desired within the refrigerant discharged from the evaporator coil and setting a desired temperature (T2set) for such discharge refrigerant by
space="preserve" listing-type="equation">T.sub.2set =T.sub.sat +T.sub.s ;a second temperature sensing means arranged adjacent to the refrigerant discharge line from the evaporator coil for measuring the temperature (T2) of the refrigerant discharged from the evaporator coil; comparator means for comparing temperature T2 with temperature T2set and providing an output comparison signal if T2 <
T2set ; and
,control means receiving the output comparison signal and providing an output control signal for controlling operation of the refrigeration system for maintaining temperature T2 equal to or above temperature T2set. - View Dependent Claims (2, 3, 4, 5)
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3. A refrigeration control system according to claim 1 wherein temperature Tsh is set to be a minimum of approximately 5°
- F.
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4. A refrigeration control system according to claim 1 further comprising third temperature sensing means arranged adjacent the inlet end of the evaporator coil for sensing the temperature (T3) of the refrigerant flowing into the evaporator coil and wherein said control means provides an output control signal for controlling operation of the refrigeration system for maintaining temperature T2 greater than temperature T3.
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5. A refrigeration control system according to claim 4 wherein said control means provides an output signal for controlling the operation of the refrigeration system for maintaining temperature T2 greater than temperature T3 by an amount sufficient to insure that all of the liquid refrigerant passing through the evaporator coil is completely transformed into a gaseous refrigerant by the time that it is discharged from the evaporator coil.
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6. A refrigeration control system for a refrigeration system including a refrigerated display case with a primary air conduit having an air outlet opening and an air inlet opening, an evaporator coil arranged within the primary air conduit for refrigerating air passing through such conduit, and an expansion valve coupled to the inlet end of the evaporator coil, said refrigeration control system comprising:
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first temperature sensing means arranged at the air discharge side of the evaporator coil for sensing the temperature (T1) of the air that has passed over the evaporator coil; a second temperature sensing means arranged adjacent to the refrigerant discharge end of the evaporator coil for measuring the temperature (T2) of the refrigerant discharged from the evaporator coil; comparator means for comparing temperature T1 with temperature T2 to determine if temperature T1 is greater than temperature T2 by a preselected temperature differential; means for setting a desired temperature differential between temperature T1 and temperature T2 for maintaining temperature T1 sufficiently above temperature T2 to assure that the refrigerant discharged from the evaporator coil is above its saturation temperature; and
,control means to provide an output control signal for controlling operation of the refrigeration system for maintaining temperature T1 sufficiently above temperature T2 by at least the set temperature differential. - View Dependent Claims (7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. A refrigeration system comprising:
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a refrigerated display case with a primary air conduit having an air outlet opening and an air inlet opening; an evaporator coil arranged within said primary air conduit for refrigerating air passing through said primary air conduit; an electronically controlled expansion valve coupled to the inlet end of said evaporator coil; and
,a refrigeration control system including;
first temperature sensing means arranged at the air discharge side of said evaporator coil for sensing the temperature (T1) of the air that has passed over said evaporator coil;
a second temperature sensing means arranged adjacent to the refrigerant discharge end of said evaporator coil for measuring the temperature (T2) of the refrigerant discharged from said evaporator coil;
comparator means for comparing temperature T1 with temperature T2 to determine if temperature T1 is greater than temperature T2 by a preselected temperature differential;
means for setting a desired temperature differential between temperature T1 and temperature T2 for maintaining temperature T1 sufficiently above temperature T2 to assure that the refrigerant discharged from said evaporator coil is above its saturation temperature; and
, control means to provide an output control signal to said electronically controlled expansion valve for controlling operation of the refrigeration system for maintaining temperature T1 sufficiently above temperature T2 by at least the set temperature differential. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23, 24, 25)
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26. A refrigeration control system for a refrigeration system including a refrigerated display case with a primary air conduit having an air outlet opening and an air inlet opening, an evaporator coil arranged within the primary air conduit for refrigerating air passing through such conduit, and an expansion valve coupled the inlet end of the evaporator coil, said refrigeration control system comprising:
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a discharge temperature sensing means arranged adjacent to the refrigerant discharge end of the evaporator coil for measuring the temperature (T2) of the refrigerant discharged from the evaporator coil; an inlet temperature sensing means arranged adjacent the inlet end of the evaporator coil for sensing the temperature (T3) of the refrigerant flowing into the evaporator coil; comparator means for comparing temperature T2 with temperature T3 to determine if temperature T2 is greater than temperature T3 by a preselected temperature differential; means for setting a desired temperature differential between temperature T2 and temperature T3 for maintaining temperature T2 sufficiently above temperature T3 to assure that the refrigerant discharged from the evaporator coil is superheated; and
,control means to provide an output control signal for controlling operation of the refrigeration system for maintaining temperature T2 sufficiently above temperature T3 by at least the set temperature differential. - View Dependent Claims (27, 28, 29, 30, 31)
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32. A refrigeration system comprising:
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a refrigerated display case with a primary air conduit having an air outlet and an air inlet opening; an evaporator coil arranged within said primary air conduit for refrigerating air passing through said primary air conduit; an electronically controlled expansion valve coupled to the inlet end of said evaporator coil; and a refrigeration system including;
a pressure sensing means arranged at the refrigerant discharge line from said evaporator coil for sensing the pressure (P) of the refrigerant within said discharge line;
means for determining the saturation temperature (Tsat) of the refrigerant from the measuring of pressure P;
means for setting a level of superheat (Tsh) desired within the refrigerant discharged from said evaporator coil and setting a desired temperature (T2set) for such discharge refrigerant by T2set =Tsat +Ts ;
a second temperature sensing means arranged adjacent to said refrigerant discharge line from said evaporator coil for measuring the temperature (T2) of the refrigerant discharged from said evaporator coil;
comparator means for comparing temperature T2 with temperature T2set and providing an output comparison signal if T2 <
T2set ; and
, control means receiving the output comparison signal and providing an output control signal for controlling operation of the refrigeration system for maintaining temperature T2 equal to or above temperature T2set. - View Dependent Claims (33, 34, 35, 36)
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34. A refrigeration system according to claim 32 wherein temperature Tsh is set to be a minimum of approximately 5°
- F.
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35. A refrigeration system according to claim 32 further comprising third temperature sensing means arranged adjacent the inlet end of said evaporator coil for sensing the temperature (T3) of the refrigerant flowing into said evaporator coil and wherein said control means provides an output control signal for controlling operation of the refrigeration system for maintaining temperature T2 greater than temperature T3.
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36. A refrigeration system according to claim 35 wherein said control means provides an output signal for controlling the operation of the refrigeration system for maintaining temperature T2 greater than temperature T3 by an amount sufficient to insure that all of the liquid refrigerant passing through the evaporator coil is completely transformed into a gaseous refrigerant by the time that it is discharged from said evaporator coil.
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Specification