An Experimental Investigation of the Effects of Wet and Dry Coil Conditions on Cyclic Performance in the SEER Procedure

In the Unites States, residential air conditioners (ACs) and heat pumps (HPs) are rated by a test procedure that estimates seasonal efficiency, or SEER. One part of the test procedure -the cyclic test determines the efficiency degradation when the AC system cycles ON and OFF. The cyclic test is presently conducted at dry coil conditions, even though most systems operate the majority of the time at wet coil conditions. In this paper, cyclic test results are presented for two AC systems one constant-speed (CS) and one variable-speed (liS) -at both wet and dry coil conditions. The results indicate that wet and dry cyclic tests are not equivalent, as had been assumed [5]. The wet coil cyclic test results in a 9% smaller SEER than the dry coil cyclic test for the CS 5ystem, and 4% smaller SEER for the vs system. A new method for conducting the cyclic test at wet coil conditions is presented. INTRODUCTION In the late 1970's, the United States Department of Energy (DOE) developed and implemented a rating procedure to determine the efficiency of residential air conditioners (ACs) and heat pumps (HPs) in the cooling mode. This procedure consists of a series of laboratory tests that manufacturers are required to perform to determine the Seasonal Energy Efficiency Ratio (SEER). The purpose of this paper is to examine one particular aspect of the test procedure: the cyclic test. Presently, the cyclic test is performed at dry coil conditions (sensible only, no moisture removal), even though most systems operate at wet coil conditions 1n the majority of applications. The cyclic performance of two AC systems is experimentally examined; one constant-speed (CS) system and one variable-speed (liS) system are tested. Tests are run at both wet and dry coil conditions and the results are compared. overview of SEER Test Procedure The SEER procedure consists of a series of steady-state and cyclic laboratory tests, which are specified in detail in the Federal Register [1], as well as ARI and ASH RAE Standards [2,3]. The required tests for a conventional, CS systems are listed in Table 1 .