Design Optimization of Low Cost Modifications to Existing Residential Air Conditioners

Photo of Minerva Corona, Jessie Guzman, Javier Paredes Students: Minerva Corona, Jessie Guzman, Javier Paredes

Sponsor: Austin Management Group

Date: Fall 2010

Requirements:
The main requirements were to build a test stand to hold two units and to install a custom evaporator coil and thermal snap switch to the modified unit. A thermal snap switch controls the blower based on the refrigerant temperature. The custom evaporator coil is a special ordered coil that is double the thickness of the original evaporator and is designed to operate in counterflow to the airflow. Spacing within the air handler unit was an important constraint since it was designed for a smaller evaporator coil.

Problem:
The goal of this project was to modify an air conditioning unit in an attempt to enhance dehumidification for increased comfort at higher thermostat setting temperatures. A higher thermostat setting reduces air conditioning operating time and electricity usage and therefore saves the user money.

Solution:
Installation of the custom evaporator coil yielded 10°F colder air temperatures than the unmodified unit. The cooler air temperatures are indicative of less humid air. The thermal snap switch functioned correctly but allowed the compressor's efficiency to reach levels that were lower than the allowed 6% efficiency drop. In order to meet the target operating efficiency range, the snap switch must be reconfigured. Ideal refrigerant temperature ranges for the snap switch were determined by experimenting with a manually activated the snap switch. Since the current snap switch operating temperature range is not configurable, it is recommended that a different snap switch be used with an operating range in line with the ideal refrigerant temperatures determined. Installing this snap switch in the air handler unit proved to potentially reduce the blower operating time by 60%. Our recommendation for this project is to implement the modifications with the custom evaporator coil and a different snap switch and test the modified unit in an actual installation.

Images related to the project:

Photo related to Design Optimization of Low Cost Modifications to Existing Residential Air Conditioners project
Photo related to Design Optimization of Low Cost Modifications to Existing Residential Air Conditioners project
Joomla SEF URLs by Artio