Studies on PCM based modular heat exchanger for free cooling application for energy management in green buildings

Abstract

The concept of Green building is gaining importance in the present energy scenario and related environmental issues. In the present work a feasibility study has been performed to assess the free cooling potential for regions with low diurnal temperature variation, using PCM-based thermal energy storage systems. Extensive numerical and CFD analysis are carried out to finalize the operating and geometrical parameters required for the design of a modular heat exchanger suitable for free cooling applications. The present research is divided into three major parts. In the first part, a numerical study and experiment on a single tube surrounded by a PCM shell is carried out. The Enthalpy method of modeling is adopted and the discretised non-dimensional form of governing equations and boundary conditions are solved by an implicit finite difference method by using MATLAB software. In the second part, the results of the numerical work obtained are used in the development of a novel modular heat exchanger that encapsulates the PCM in the shell portion of the module and the passage for the flow of air through the tubes. In the third part, an experimental investigation is made to study the performance of the modular heat exchanger selected for free cooling. The PCM is selected based on the climatic condition of the region selected for the study. The performance of the building is tested for various heating load conditions of 1, 2 and 3 kW, and the effectiveness of the free cooling is evaluated. A CFD analysis has also been carried out for the charging condition carried out in the experiment and the results are presented. The concept of storing the free cool energy available during the early morning hours and utilizing it for day time cooling requirement is demonstrated for location with low diurnal temperature variation. The conclusions from the numerical, CFD analysis and experiments are presented at the end. newline