Solar Absorption Cooling and Heating System in the Intelligent Workplace

Abstract

A solar thermal driven absorption cooling and heating system has been installed in Carnegie Mellon University’s Robert L. Preger intelligent Workplace, the IW. The purpose of this solar installation is to investigate the technical and economic aspects of using high temperature solar thermal receivers driving a two stage absorption chiller to cool and heat a building space. The solar system consists primarily of 52 m2 of single-axis tracking parabolic trough solar collectors (PTSC), and a 16 kW double effect absorption chiller driven by either a fluid heated in solar receivers or by natural gas fuel. The receivers convert solar radiation to thermal energy in a heated fluid; the chiller then uses this energy in summer to generate chilled water. In winter, the thermal energy is directly used for heating. A performance analysis was carried out to estimate the conversion efficiency of the PTSC based on mass and energy balances and heat transfer computations programmed in Engineering Equation Solver (EES). The performance of the overall solar cooling and heating for the IW has been programmed in TRNSYS modeling system. This solar energy system has been estimated to provide 38–50% of the cooling and 9–30% of heating energy depending upon orientation, insulation and storage capacity for 245 m2 of space in the IW. Experimental data are now being collected and will be used for validating the solar collector model. The solar system model will be used in interpreting the data yet to be obtained on the system performance. The primary purpose of this research program is the development of systems which reduce the energy requirements for the operation of buildings by a factor of two or greater, and the provision of techniques and tools for the design and evaluation of such systems.