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Application notes
Using Pressure Transducers to Minimize Superheat in Air Conditioning and Refrigeration Systems
Controlling Superheat
Industrial air conditioning units create comfortable environments in industrial facilities where efficiency and performance count. Air conditioner control must extend to complex, multi-zone environments with varying humidity and temperature preferences. Typical compressor-driven industrial air conditioning units use the refrigeration cycle. The refrigeration system consists of an evaporator, a compressor, a condenser, an expansion valve, and system monitoring devices including temperature and pressure transducers. The air conditioning refrigeration cycle is described below:
- Cool, low pressure gaseous refrigerant enters the compressor
- Hot, high pressure gaseous refrigerant leaves the compressor and enters the condenser
- Hot, high pressure gaseous refrigerant in the condenser releases heat to the outside environment
- Warm, high pressure liquid refrigerant leaves the condenser coil and enters the expansion valve
- Expansion valve reduces pressure and temperature of the liquid refrigerant
- The cold, low pressure gaseous refrigerant absorbs heat to cool the inside environment
- Refrigerant leaves the condenser as a cool, low pressure gas, and the cycle repeats itself
As efficiency and energy conservation gain importance in modern society, precision control of the refrigeration cycle has emerged as a simple method to greatly increase the efficiency of air conditioning and refrigeration systems. Superheat is define as the difference in temperature between the boiling temperature of the refrigerant and the actual temperature of the refrigerant as it leaves the evaporator coil.
Superheat cannot be completely eliminated, but it can be minimized to improve efficiency. This can be accomplished through continuous pressure and temperature measurement using electronic temperature and pressure transducers at the evaporator coil outlet and at the compressor inlet.
Pressure and temperature measurement provides the information necessary to allow the electronic expansion valve to maximize the efficiency of the air conditioning unit. Automated air conditioning and refrigeration control processes depend on accurate, reliable temperature and pressure transducers.
Using Pressure Transducers to Control Superheat in Industrial Air Conditioning Applications
Pressure transducers are used for the control of superheat in the following industrial air conditioning applications:
- Evaporator Coil Outlet Pressure
- Compressor Inlet Pressure
- Evaporator Coil Outlet Temperature (with WIKA Electronic Temperature products)
- Compressor Inlet Temperature (with WIKA Electronic Temperature products)
- Expansion Valve Flow Rate Monitoring
Controlling the superheat in industrial air conditioning applications requires pressure transducer compatibility with various refrigerants and wide range of pressures. Pressure transducers provide the pressure measured at the evaporator outlet and the compressor inlet, as well as monitoring and regulating the flow rate of refrigerant through the expansion valve. The WIKA R-1 and AC-1 electronic pressure transducers have been designed for performance, reliability, and compatibility with all common refrigerants in industrial air conditioning refrigeration applications.
Pressure Transmitter Selection Considerations:
- High accuracy
- High repeatability
- Compatibility with refrigerants
- Condensation proof