Cutaway view of Trane's electronic expansion valve.

Electronic Expansion Valve 

When coupled with Trane’s Adaptive Control™ microprocessor, our electronic expansion valve significantly improves part-load performance of the Series R chiller by minimizing superheat in the evaporator and allowing the chiller to run at reduced condensing temperatures. Chillers which use conventional TXV’s must run at higher head pressures and consume more power than necessary at part-loads. Additionally, the electronic expansion valve and its controls allow much better stability and control over dynamic load and head changes. Under these conditions a conventional TXV may never achieve control stability and extended periods of TXV "hunting" and liquid slugging are common. 

Capacity Control and Load Matching 

Infinitely variable compressor modulation allows the compressor capacity to exactly match the building cooling load. Reciprocating chillers that rely on stepped capacity control must run at a capacity equal to or greater than the load. Much of this excess capacity is lost because overcooling goes toward building latent heat removal, causing the building to be dried beyond normal comfort requirements. The result is an increase in chiller energy costs, particularly at the part-load conditions at which the chiller operates most of the time. 

PID Chilled Water Setpoint Control Through Slide Valve Modulation 

Maintain Chilled Water Supply Within ±½ F Of Setpoint 

Reciprocating chillers that have step capacity control typically can only maintain water temperature to around ± 2 F. With the air-cooled Series R chiller, maintaining temperature control has never been so accurate. 

Reduce Compressor Cycling 

Modulating capacity control offers better compressor reliability. Compressor cycling, typical of reciprocating compressors, will decrease compressor component life. Parts like motors and valves do not stand up well to excessive compressor cycling.