EEVs Make Low Condensing Refrigeration a Reality
It’s a problem all operators face: if I lower the head pressures in my refrigeration systems, I can lower operating costs. On top of that, I can meet the Department of Energy’s 2017 energy reduction targets. But, how do I do that with existing technologies?
Some in the industry have tried using thermal expansion valves (TXV) to lower head pressures, but TXVs can’t maintain capacity and digest flash gas that forms when pressures float lower. So operators are still forced to keep head pressures near 105 °F.
Enter the electronic expansion valve (EEV). With technology advances, EEVs can not only modulate to handle capacity changes, they can also digest flash gas and control superheat. Now operators can float system pressures to 70 °F or lower. As the condensing temperature drops, the BTU/hr increases, reducing compressor run hours. In addition, the long-term reliability of the compressors increases because of the lower temperatures and discharge pressures. For every 10 °F decrease in head pressure, a system can achieve 15–20 percent energy efficiency ratio improvement on compressor performance.
A Partnership That’s More Than the Sum of Its Parts
There are two key components in low condensing systems: the EEV and the superheat controller. Because of its patented ceramic gate port design, Emerson Climate Technologies’ EX Series EEV allows for a wide range of condensing pressures. Its stepper motor delivers precise refrigerant control, with capacity modulation from 10 to 100 percent. Driving the stepper motor is the XEV EX48 superheat controller, which regulates evaporator superheat and optimizes system performance. The XEV EX48 also allows operators to see the superheat value, percentage valve opening, or pressure and temperature values through its integral display. Working hand in hand, these two technologies allow operators to increase energy savings, pull-down rates and compressor life.
Low condensing is getting attention from regulators as well. In its Title 24 regulation, the state of California included a requirement calling for a minimum setpoint of at least 70 °F in floating head pressure systems. In addition, the Department of Energy’s guidelines for meeting 2017 energy reduction targets suggest floating head pressures using EEVs for walk-in units.
This blog is a summary of “The High Potential of Low Condensing Refrigeration” Solution Spotlight in the latest edition of Emerson Climate Technologies’ E360 Outlook. Read the article in its entirety and download the digital edition.