Optimal Sequencing of Central Refrigeration Equipment in an Industrial Plant

Abstract

A model was developed to find a viable solution to the problem of selecting the optimal sequence of refrigeration equipment (chillers, cooling towers, pumps) to operate in a Central Utility Plant. The optimal equipment sequence is that sequence which has the lowest energy cost to operate at a given plant cooling load and outside air wet bulb temperature. and satisfies all the constraints associated with the refrigeration system. Selection of the optimal equipment sequence is very difficult given the complexity of the refrigeration system and the dynamic nature of the plant cooling load. As a solution a computer program was developed to generate optimal equipment sequences to operate for combinations of a wide range of plant cooling loads and outside air wet bulb temperatures. Analysis of the solution identified the need for a retrofit project to remove "vital" constraints in order to improve the refrigeration system's performance. The solution to the problem was then incorporated in the operating procedures for the Central Utility Plant.