In refrigeration and air conditioning systems, the thermostatic expansion valve (TEV) can be a difficult device to understand, install, adjust, and troubleshoot. It's never a waste of time to review TEVs - their operating principles, installation, maintenance, and troubleshooting. In a nutshell, the role of the TEV is to control liquid injection into an evaporator as a function of the load. The controlling parameter is superheat at the evaporator. As the load on the evaporator increases, the valve responds to an increase in superheat and opens to allow more liquid refrigerant to flow into the evaporator. In so doing, the TEV maximises the usable evaporator heat transfer surface and protects the compressor by making sure that only vapor returns to it.
展开▼
