Development of Test Protocol for Direct Evaporative Condenser Air Precoolers

Evaporative precoolers for air-cooled condensing units have been demonstrated to reduce electricity demand and save energy, particularly in arid climates. However, no objective, standardized test data for these products exists in the United States, making it difficult for end-users and utilities to evaluate expected performance prior to purchase and installation. This paper proposes a test protocol for evaporative precoolers installed on condensing units up to 70 kW, and then executes the protocol using three precooling products designed for residential split system air conditioners. Several methods of evaluating performance are compared and a method called the equivalent performance method is proposed. Without direct measurements, the method determines the equivalent temperature reduction of the condenser inlet air due to the precooler. While the performance of the products tested was poor, the products were selected based on convenience and are not expected to be representative of the market.