US 4,325,223 AGranted

Energy management system for refrigeration systems

OwnerRobert J. Cantleyinventor

Life of this patent

Estimating the term…

Loading patent…

Abstract

A system and method for managing energy in large refrigeration systems and the like by continuously monitoring operating parameters and controlling to optimize the refrigeration system elements. A multiplicity of remote sensors is disposed at the appropriate points in the refrigeration system to produce analog electrical signals representative of various temperatures such as wet bulb temperature, dry bulb temperature, condensing temperature, evaporator air temperature, evaporator refrigerant temperature, and similar temperatures, and various pressures such as head pressure, booster suction pressure, intermediate suction pressure, and the like. A signal processor is provided to receive signals from the sensors, to condition the analog signals, convert to digital signals and to feed a digital computer which has a memory for storing system design parameters and refrigerant characteristics. The digital computer calculates the instantaneous system operating parameters from the digital signals, compares these parameters to the design parameters, and operates control relays to load and unload compressors to maintain optimum system pressures, to energize and deenergize fans and pumps in accordance with the system requirements, and to produce alarms when non-condensible gases and/or fouled condensers are indicated in the refrigeration system. In systems subject to frost build up on the evaporator, defrost cycles are also controlled by the computer to occur only when necessary.

Claims35

Dependent claims

An energy management system for a single stage refrigeration system having evaporative type condensers comprising:

A. a plurality of electrical temperature sensors attached to said refrigeration system, said sensors producing electrical signals representative of operating parameters of said refrigeration system including
a. wet bulb temperature,
b. dry bulb temperature,
c. condensing temperature, and
d. ambient temperature;
B. a plurality of electrical pressure sensors attached to said refrigeration system, said pressure sensors producing electrical signals representative of operating parameters of said refrigeration system including
a. head pressure, and
b. suction pressure;
C. signal processing circuits connected to said temperature sensors and said pressure sensors for receiving said respective electrical signals therefrom for producing a sequence of binary digital signals representative of said electrical signals;
D. computer means connected to said signal processing circuits for receiving said sequence of binary digital signals, said computer means having memory means for storing system design parameters, said computer means programmed to periodically calculate other operating parameters of said refrigeration system including
a. relative humidity,
b. efficiency of said refrigeration system,
c. temperature difference between said condensing temperature and said wet bulb temperature,
d. difference between said head pressure and said suction pressure, and
e. the cost to operate said refrigeration system;
E. control relays connected to said computer means for controlling, in said refrigeration system,
a. condenser fans in response to calculated value of said difference between said condensing temperature and said wet bulb temperature,
b. condenser pumps responsive to the calculated value of said difference between said condensing temperature and said wet bulb temperature, and
c. compressor loading responsive to calculated value of said diffference between said head pressure and said suction pressure;
and
F. first alarm means responsive to a deviation of said head pressure relative to said condensing temperature to indicate presence of non-condensible gases in said refrigeration system, and second alarm means responsive to said difference between said condensing temperature and said wet bulb temperature to indicate fouled condensers in said refrigeration system.

18 more elements

An energy management system for a double stage refrigeration system having evaporative type condensers, booster compressors, and main compressors, comprising:

A. a plurality of electrical temperature sensors attached to said refrigeration system, said sensors producing electrical signals representative of the following operating parameters of said refrigeration system,
a. wet bulb temperature,
b. dry bulb temperature,
c. condensing temperature,
d. evaporator air temperature,
e. evaporator refrigerant temperature, and
f. ambient temperature;
B. a plurality of electrical pressure sensors attached to said refrigeration system, said pressure sensors producing electrical signals representative of the following operating parameters of said refrigeration system
a. head pressure,
b. intermediate suction pressure, and
c. booster suction pressure;
C. signal processing circuits connected to said temperature sensors and said pressure sensors for receiving said respective electrical signals therefrom for producing a sequence of binary digital signals representative of said respective electrical signals;
D. computer means connected to said signal processing circuits for receiving said sequence of binary digital signals, said computer means having memory means for storing system design parameters, said computer means programmed to periodically calculate other operating parameters of said refrigeration system
a. relative humidity,
b. efficiency of said refrigeration system,
c. temperature difference between said condensing temperature and said wet bulb temperature,
d. difference between said head pressure and said booster suction pressure,
e. the cost to operate said refrigeration system, and
f. difference between said evaporator air temperature and said evaporator refrigerant temperature;
E. control relays connected to said computer means for controlling, in said refrigeration system,
a. condenser fans in response to the calculated value of said difference between said condensing temperature and said wet bulb temperature,
b. condenser pumps responsive to the calculated value of said difference between said condensing temperature and said wet bulb temperature, and
c. compressor loading responsive to calculated value of said difference between said head pressure and said booster suction pressure;
and
F. first alarm means responsive to a deviation of said head pressure relative to said condensing temperature to indicate presence of non-condensible gases in said refrigeration system, and second alarm means responsive to said difference between said condensing temperature and said wet bulb temperature to indicate fouled condensers in said refrigeration system.

22 more elements

An energy management system for a refrigeration system or the like having evaporative condensers comprising:

first temperature sensing means for producing a first signal representative of the web bulb temperature in and around said condensers;
second temperature sensing means for producing a second signal representative of the condensing temperature of said refrigeration system;
pressure sensing means for producing a third signal representative of the head pressure of said refrigeration system;
memory means for storing pressure-temperature data representative of the head pressure/condensing temperature relationship of the refrigerant of said refrigeration system, and a design difference-temperature between the design wet bulb temperature and the design condenser temperature;
and
calculation means connected to said first and second temperature sensing means for receiving said first and second signals, to said pressure sensing means for receiving said third signal and to said memory means, said calculation means for comparing the sensed head pressure and the sensed condensing temperature to said pressure-temperature data in said memory, and for calculating the difference between said sensed wet bulb temperature and said sensed condensing temperature, and for comparing such difference temperature to said design difference-temperature stored in said memory, said calculation memory means thereby determining the efficiency of said refrigeration system.

3 more elements

In a single stage refrigeration system having evaporate condensers, the method of managing energy in the system to minimize operating costs comprising the steps of:

storing in a memory the pressure and condensing temperature characteristics of the refrigerant, the design value of the web bulb temperature in the condensers, the design value of condensing temperature, the design value of the head pressure, the design value of the suction pressure, and the cost per ton per hour for maximum load;
monitoring electrically the operational parameters of dry bulb temperature, web bulb temperature, head pressure, condensing temperature, and suction pressure;
processing the monitored electrical signals for input to a digital computer;
periodically calculating in the computer the relationship of the head pressure and the condensing temperature during operation of the refrigeration system;
comparing such relationship to the stored characteristics of the refrigerant;
energizing a non-condensible gases alarm when such relationship deviates from the stored relationship;
calculating in the computer the temperature difference between the condensing temperature and the web bulb temperature;
comparing such temperature difference to the difference between the stored design condensing temperature and design wet bulb temperature;
energizing a fouled condenser alarm when such calculated temperature difference is greater than such stored design difference;
deenergizing condenser fans and condenser pumps when such temperature difference is a selected value less than such stored difference;
calculating in the computer the pressure difference between the head pressure and the suction pressure;
comparing such pressure difference to the difference between the stored design head pressure and stored design suction pressure;
correcting the stored cost per ton per hour for a maximum load when such calculated pressure difference is less than such stored difference;
and
displaying the corrected cost per ton per hour.

12 more elements

In a two stage refrigeration system having booster compressors, main compressors, and evaporative condensers, the method of managing energy in the system to minimize operating costs comprising the steps of:

storing in a memory the pressure and condensing temperature characteristics of the refrigerant, the design value of the wet bulb temperature in the condensers, the design value of condensing temperature, the design value of the head pressure, the design value of the booster suction pressure, the design value of the intermediate suction pressure, and the cost per ton per hour for maximum load;
monitoring electrically the operational parameters of dry bulb temperature, wet bulb temperature, head pressure, condensing temperature, booster suction pressure, intermediate suction pressure, evaporator air temperature, and evaporator refrigerant temperature;
processing the monitored electrical signals for input to a digital computer;
periodically calculating in the computer the relationship of the head pressure and the condensing temperature during operation of the refrigeration system;
comparing such relationship to the stored characteristics of the refrigerant;
energizing a non-condensible gases alarm when such relationship deviates from the stored relationship;
calculating in the computer the temperature difference between the condensing temperature and the wet bulb temperature;
comparing such temperature difference to the difference between the stored design condensing temperature and design wet bulb temperature;
energizing a fouled condenser alarm when such calculated temperature difference is greater than such stored design difference;
deenergizing condenser fans and condenser pumps when such temperature difference is a selected value less than such stored difference;
calculating in the computer the pressure difference between the head pressure and the booster suction pressure;
comparing such pressure difference to the difference between the stored design head pressure and stored design booster suction pressure;
correcting the stored cost per ton per hour for a maximum load when such calculated difference is less than such stored difference;
and
displaying the corrected cost per ton per hour.

12 more elements

Dependencies are inferred from the claim text.