U.S. Department of Energy
Federal Energy Management Program

Excerpts from

Federal Technology Alert

Liquid Refrigerant Pumping - Technology for Improving Refrigeration Performance and Capacity

"The liquid refrigerant pump (LRP) is a simple, reliable means of increasing the capacity and efficiency of new and existing refrigeration and air conditioning systems. To benefit from the technology, the target system must employ a direct-expansion evaporator and minimum head pressure controls. Many package HVAC, small chiller, and refrigerated display case system fit these application criteria. The LRP reduces compressor load by compensating for the pressure drop through the liquid line and filter/dryer and prevents boiling (flash gas formation) between the condenser and the expansion valve. The discharge pressure setpoint may then be lowered to obtain significant compressor load reduction in cool weather. Annual energy savings typically range from 10 to 30% and paybacks of under two years are usually realized."

"This Federal Technology Alert provides detailed information and procedures that a federal energy manager needs to evaluate most LRP applications. The New Technology Demonstration Program (NTDP) technology selection process and general benefits to the federal sector are outlined. Principles of refrigeration and LRP energy-saving mechanisms are explained, procedures are given for preliminary sizing of equipment, estimating energy savings, and calculating life-cycle cost (LCC). Proper application, installation, and operations and maintenance (O&M) impacts are discussed. A federal-sector case study is presented to give the reader a good sense of what is really involved in implementing this technology. A list of federal sector users and a bibliography are included for prospective users who have specific or highly technical questions not fully addressed in the alert. Details on LCC analysis, a sample Energy Conservation Investment Program (ECIP) form, a sample procurement specification, and an application checklist are also provided."

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