Vapor compression system

Abstract

A vapor compression system having a defrost cycle is disclosed. A compressor, a condenser, an evaporator, and an expansion valve connected in a closed refrigerant loop with at least one flow control device. The at least one flow control device may control the flow of refrigerant through the closed refrigerant loop. At least one sensor monitors a predetermined parameter of the closed refrigerant loop and at least one controller receives a signal from the at least one sensor. The at least one controller controls the position of the at least one flow control device. The at least one controller initiates a defrost cycle in the closed refrigerant loop by substantially actuating at least one of the at least one flow control device to provide refrigerant flow from the compressor to the evaporator for substantially preventing formation of frost on the evaporator.

1 . A vapor compression system comprising:
 a compressor, a condenser, an evaporator, and an expansion valve connected in a closed refrigerant loop;   at least one flow control device configured to control the flow of refrigerant through the closed refrigerant loop;   at least one sensor configured to monitor a predetermined parameter of the closed refrigerant loop;   at least one controller configured to receive a signal from the at least one sensor, the at least one controller configured to actuate the at least one flow control device; and   the at least one controller configured to initiate a defrost cycle in the closed refrigerant loop by actuating at least one of the at least one flow control device to provide refrigerant flow from the compressor to the evaporator for substantially preventing formation of frost on the evaporator.   
   
   
       2 . The system of  claim 1 , wherein refrigerant flow from the compressor is provided to the condenser upstream of the evaporator. 
   
   
       3 . The system of  claim 1 , wherein the at least one controller controls the position of the at least one flow control device based on the predetermined parameter of the closed refrigerant loop. 
   
   
       4 . The system of  claim 1 , wherein the predetermined parameter of the closed refrigerant loop is the temperature of the evaporator. 
   
   
       5 . The system of  claim 1 , wherein the predetermined parameter of the closed refrigerant loop is the pressure level of the evaporator. 
   
   
       6 . The system of  claim 4 , wherein the at least one controller initiates the defrost cycle when the temperature of the evaporator reaches a predetermined temperature. 
   
   
       7 . The system of  claim 5 , wherein the controller initiates the defrost cycle when the pressure of the evaporator reaches a predetermined pressure. 
   
   
       8 . The system of  claim 1 , wherein the flow control device is a valve. 
   
   
       9 . The system of  claim 1 , wherein the vapor compression system is a heat pump system. 
   
   
       10 . A defrost cycle for a vapor compression system comprising:
 a vapor compression system comprising a compressor, a condenser, an evaporator, a flow control device and an expansion valve connected in a closed refrigerant loop, the flow control device disposed between the compressor and the evaporator;   a controller configured to control an extent of actuation of the flow control device based on a predetermined parameter of the closed refrigerant loop;   wherein in response to the predetermined parameter of the closed refrigerant loop being met, the activated flow control device provides refrigerant flow from the compressor to the flow control device to the evaporator, thereby raising the temperature of the evaporator and substantially eliminating the formation of frost on the evaporator.   
   
   
       11 . The defrost cycle of  claim 10 , wherein the predetermined parameter of the closed refrigerant loop is an evaporator temperature. 
   
   
       12 . The defrost cycle of  claim 10 , wherein the predetermined parameter of the closed refrigerant loop is an evaporator pressure. 
   
   
       13 . The defrost cycle of  claim 10 , wherein the flow control device is a valve. 
   
   
       14 . The defrost cycle of  claim 10 , wherein the vapor compression system is a heat pump. 
   
   
       15 . A method for defrosting an evaporator in a vapor compression system comprising the steps of:
 providing a compressor, a condenser, an evaporator, and an expansion valve connected in a closed refrigerant loop;   disposing at least one flow control device in the closed refrigerant loop;   monitoring a predetermined parameter of the closed refrigerant loop with at least one sensor; and   sending a signal from the at least one sensor to at least one controller;   controlling the position of the at least one flow control device with at least one of the at least one controller based on the signal received from the at least one sensor to initiate or cancel a defrost cycle on the evaporator.   
   
   
       16 . The method of  claim 15 , wherein the step of disposing the at least one flow control device further comprises the flow control device routing the refrigerant flow discharge from the compressor to the condenser, and the refrigerant flow discharge from the condenser to the evaporator. 
   
   
       17 . The method of  claim 16 , wherein the step of controlling the position of the flow control device further comprises the flow control device routing the refrigerant flow discharge from the compressor to the evaporator. 
   
   
       18 . The method of  claim 15 , wherein the step of monitoring a predetermined parameter of the closed refrigerant loop comprises monitoring evaporator temperature. 
   
   
       19 . The method of  claim 15 , wherein the step of monitoring a predetermined parameter of the closed refrigerant loop comprises monitoring evaporator pressure. 
   
   
       20 . The method of  claim 15 , wherein the step of disposing a flow control device in the closed refrigerant loop further comprises disposing a valve in the closed refrigerant loop. 
   
   
       21 . A vapor compression system comprising:
 a compressor, a condenser, an evaporator, and an expansion valve connected in a closed refrigerant loop;   at least one flow control device configured to control the flow of refrigerant through the closed refrigerant loop;   at least one sensor configured to monitor a predetermined parameter of the evaporator;   at least one controller configured to receive a signal from the at least one sensor, the at least one controller configured to control a position of the at least one flow control device; and   the at least one controller configured to initiate a defrost cycle in the closed refrigerant loop by actuating at least one of the at least one flow control device to provide refrigerant flow from the compressor to the evaporator for substantially preventing formation of frost on the evaporator.   
   
   
       22 . The system of  claim 21 , wherein the at least one sensor is disposed on a cooling fin of the evaporator. 
   
   
       23 . A vapor compression system comprising:
 at least one compressor, at least one condenser, at least one evaporator, and at least one expansion valve connected in at least one closed refrigerant loop;   at least one flow control device configured to control the flow of refrigerant through the at least one closed refrigerant loop;   at least one sensor configured to monitor a predetermined parameter of the at least one evaporator;   at least one controller configured to receive a signal from the at least one sensor, the at least one controller configured to control a position of the at least one flow control device; and   the at least one controller configured to initiate a defrost cycle in the at least one closed refrigerant loop by actuating at least one of the at least one flow control device to provide refrigerant flow from the at least one compressor to the at least one evaporator for substantially preventing formation of frost on the at least one evaporator.   
   
   
       24 . The system of  claim 23 , wherein one defrost cycle is initiated at a time.