Refrigeration system and control method for refrigeration system

Abstract

A control system for a refrigeration system, the control system comprising a plurality of processors that are collectively arranged to: receive system operation data indicative of a first temperature or pressure at a first location in the refrigeration system at a first time; compare the temperature or pressure to a threshold value, based on the comparison, output a control signal to alter an operating parameter of the refrigeration system; receive further system operation data indicative of a second temperature or pressure at the first location in the refrigeration system at a second time; compare the further temperature or pressure to the threshold value; and based on a determination that the second temperature or pressure is on the same side of the threshold as the first temperature or pressure, output a warning signal indicative of a leak in a compressor of the refrigeration system.

1 . A control system for a refrigeration system, the control system comprising a plurality of processors that are collectively arranged to:
 receive system operation data indicative of a first temperature or pressure at a first location in the refrigeration system at a first time;   compare the temperature or pressure to a threshold value,   based on the comparison, output a control signal to alter an operating parameter of the refrigeration system;   receive further system operation data indicative of a second temperature or pressure at the first location in the refrigeration system at a second time;   compare the further temperature or pressure to the threshold value; and   
       based on a determination that the second temperature or pressure is on the same side of the threshold value as the first temperature or pressure, output a warning signal indicative of a leak in the refrigeration system. 
     
     
         2 . The control system of  claim 1 , wherein the first temperature or pressure is a compressor discharge temperature at the first time, wherein the second temperature or pressure is a compressor discharge temperature at the second time, and wherein the threshold value is a compressor discharge temperature threshold value. 
     
     
         3 . The control system of  claim 2 , wherein the plurality of processors are collectively arranged to determine the compressor discharge temperature threshold value based on:
 a temperature set point of the refrigeration system,   a return air temperature of the refrigeration system,   an ambient environmental temperature,   an opening state of one or more expansion valves, and/or   a compressor speed.   
     
     
         4 . The control system of  claim 1 , wherein the plurality of processors are collectively arranged to:
 receive further system operation data indicative of a compressor suction pressure in the refrigeration system at the first time;   compare the compressor suction pressure to a compressor suction pressure threshold value,   based on the comparisons, output the control signal to alter the operating parameter of the refrigeration system;   receive further system operation data indicative of the compressor suction pressure in the refrigeration system at the second time;   compare the further compressor suction pressure to the compressor suction pressure threshold value; and   based on a determination that the compressor suction pressure at the second time is on the same side of the compressor suction pressure threshold value as the compressor suction pressure at the first time and that the compressor discharge temperature at the second time is on the same side of the compressor discharge temperature threshold value as the compressor discharge temperature at the first time, output the warning signal.   
     
     
         5 . The control system of  claim 1 , wherein the first temperature or pressure is a compressor suction pressure at the first time, wherein the second temperature or pressure is a compressor suction pressure at the second time, and wherein the threshold value is a compressor suction pressure threshold value. 
     
     
         6 . The control system of  claim 5 , wherein the compressor suction pressure threshold is equal to or less than atmospheric pressure. 
     
     
         7 . The control system of  claim 4 , wherein the plurality of processors are arranged to determine the compressor suction pressure threshold based on a return air temperature of the refrigeration system. 
     
     
         8 . The control system of  claim 1 , wherein the plurality of processors are collectively arranged to:
 receive a return air temperature value from a return air temperature sensor;   compare the return air temperature value to a return air temperature threshold, and   output the warning signal based on the determination that second temperature or pressure is on the same side of the threshold as the first temperature or pressure and a determination that the return air temperature is greater than the return air temperature threshold.   
     
     
         9 . The control system of  claim 1 , wherein the plurality of processors are collectively arranged to:
 compare an ambient temperature value for the refrigeration system to an ambient temperature threshold, and   output the warning signal based on the determination that the second temperature or pressure is on the same side of the threshold as the first temperature or pressure and a determination that the ambient temperature is less than the ambient temperature threshold.   
     
     
         10 . The control system of  claim 1 , wherein the plurality of processors are collectively arranged to:
 compare an expansion valve opening state for the refrigeration system to an expansion valve opening state threshold, and   output the warning signal based on the determination that the second temperature or pressure is on the same side of the threshold as the first temperature or pressure and a determination that the expansion valve opening state is greater than the expansion valve opening state threshold.   
     
     
         11 . The control system of  claim 1 , wherein the threshold value is a first threshold value, and wherein the plurality of processors are collectively arranged to:
 compare the first and/or second temperature or pressure to a second threshold value, the second threshold value being different from the first threshold value, and   shut down the refrigeration system based on the comparison.   
     
     
         12 . The control system of  claim 1 , wherein the operating parameter is a compressor speed, a throttle valve opening or a hot-gas by-pass duty cycle, and wherein the control signal is arranged to: reduce a compressor speed, open a throttle valve, and/or increase a hot-gas by-pass duty cycle. 
     
     
         13 . A refrigeration system comprising:
 a compressor arranged to increase the pressure of a working fluid;   a condenser arranged to allow heat transfer from the working fluid;   an expansion valve arranged to decrease the pressure of the working fluid;   an evaporator arranged to allow heat transfer to the working fluid; and   a control system according to  any preceding claim .   
     
     
         14 . The refrigeration system of  claim 13 , wherein the compressor is an open drive compressor. 
     
     
         15 . A method of controlling a refrigeration system, the method comprising:
 receiving system operation data indicative of a first temperature or pressure at a first location in the refrigeration system at a first time;   comparing the temperature or pressure to a threshold value,   based on the comparison, outputting a control signal to alter an operating parameter of the refrigeration system;   receiving further system operation data indicative of a second temperature or pressure at the first location in the refrigeration system at a second time;   comparing the further temperature or pressure to the threshold value; and   based on a determination that the second temperature or pressure is on the same side of the threshold value as the first temperature or pressure, output a warning signal indicative of a leak in the refrigeration system.