Procedure for Applying an Open-Cycle Heat Pump to An Existing Evaporator

Abstract

An open-cycle heat pump, or mechanical vapor compression (MVC) system, is often an attractive technique for increasing the energy efficiency of an evaporator. With proper design, an MVC system is capable of dramatic cost savings when retrofitted to an existing evaporator. This is especially true if the evaporator is a single or double effect design. Many such evaporators were built when energy was cheap, or because a particular process is not amenable to modern designs incorporating many effects. Advances in compressor design have made MVC applicable to a broader range of processes than ever before. This paper discusses the basic steps required to apply MVC as a retrofit to an existing evaporator. Because of their importance to identification of candidate applications, this paper emphasizes the preliminary analysis and premonitoring steps. For illustration purposes the authors refer to an MVC retrofit in progress at a plant operated by Kraft, Inc. The project is cofunded by the New York State Energy Research and Development Authority (Albany, NY), and will serve as a demonstration site to facilitate increased adoption of MVC by other industrial firms.