Valve regulators in refrigeration systems
Valves perform a variety of functions in refrigeration systems. They are used for expansion of vapour, regulating flow of water or vapour, pressure and temperature regulation, activating a device, oil level control etc. Depending on the function there are various types of valves available viz. expansion valves, stop & regulating valves, solenoid valves, safety valves, pressure controlled valves, etc.
Valve regulators are used for many different functions in commercial and industrial refrigeration like capacity regulation, condensing pressure regulation, evaporation pressure regulation, receiver pressure regulation, crankcase pressure regulation etc.
Capacity valve regulators adjust compressor capacity to actual evaporator load in applications like air driers and water chillers where the evaporating temperature is around 0 deg C. They maintain compressor suction pressure by injecting hot / cool gas from the higher pressure side. When pressure drops at the outlet these valve regulators open up to achieve pressure regulation.
They are hermetically sealed and made of bimetal as well as stainless steel.
Condenser pressure regulators can be mounted in either the gas or liquid side of the condenser in refrigeration and air conditioning systems. In systems using air cooled condensers, these valve regulators are used to maintain a steady and sufficiently high condensing pressure.
To ensure adequate pressure in the receiver there are used in conjunction with pressure valves. Valve regulators that are electronically operated are used in refrigeration systems in conjunction with electronic controls.
The range includes electronically operated expansion valves in refrigeration systems that use fluorinated refrigerants and ammonia, evaporating pressure valves and pilot valves that enable remote operation of a PM (pilot operated main) main valve.
The pilot valve regulator is used to maintain a constant pressure at the PM main valve inlet side and can control accurately the temperature of a medium from an air or liquid cooler through suction pressure regulation.
Flow regulators are used in many places in refrigeration systems. One such regulator is an automatic flow regulator that maintains constant flow rate of liquid to the evaporator. It also serves as a check valve to prevent back flow into the liquid line from the evaporator during pressure reversals such as those occurring during hot gas defrost.
There are also fixed flow valve regulators used as liquid flow control device in liquid recirculation systems. They establish and maintain constant flow rate irrespective of inlet pressure drop or changes in the inlet or outlet pressure.
Recently integrated valve stations that perform up to six different regulating functions are available. They have stop valve module, solenoid valve module, electronic expansion valve module, check valve module, motor valve module, manual regulating and opening valve modules.
They replace series of conventional mechanical, electro mechanical and electronically operated valves. These stations are designed to operate in low as well as high pressures in liquid, hot gas and compressor injection lines.
They are very flexible with each function component being individually removable for service. The valve stations can handle all common non flammable refrigerants including CO2 and non corrosive gases and liquids. They have maximum working pressure of 52 bars.
These integrated valve stations have low weight and compact design and direct weld connections.
Image is a courtesy of Teklab and show an innovative oil level control for compressor crank case
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2 Responses to “Valve regulators in refrigeration systems”
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Think Engineering
With a huge focus on the cost of energy consumption in the current market, is there any new developments being made with regard cutting down defrost times to increase energy effeciencies??
Lotusworks.com
for refrigeration expansion valve Fisher Type phenumatic control. If new or speare of phenumatic control box.
Thank You,
GEETHA ENTERPRISES.
MARINE AIR CONDITIONING & REFRIGERATION.
VISAKHAPATNAM