Affiliation:
1. Department of Energy and Power Engineering, Northeast Electric Power University, Jilin 132013, China
2. State Grid Jilin Electric Power Research Institute, Changchun 130021, China
Abstract
The diffuser is a critical component in a heat storage tank, and its structure has an important influence on the thermal performance of the heat storage tank. At present, research on the structure of diffusers often focuses on the change of one single parameter, which results in the need for a comprehensive structure analysis of diffusers in heat storage tanks. This paper comprehensively considers the inlet diameter, hole distance, and hole diameter of the diffuser and the inlet conditions of the heat storage tank. Then, a new evaluation index, namely the non-uniformity coefficient of the diffuser, is proposed. The experiments verify the accuracy of numerical calculation, and the related empirical formula is summarized finally. The results show that the diffuser with a small non-uniformity coefficient can achieve thin temperature stratification and higher exergy efficiency. In other words, the non-uniformity coefficient is in good agreement with temperature stratification and the exergy efficiency of the heat storage tank. When the flow rate of the inlet device is 0.5 m/s, the exergy efficiency increases by nearly 30 percentage points and the non-uniformity coefficient of the No. 4 diffuser is 3.39%. In contrast, that of the No. 8 diffuser is 75.17%. This evaluation index is suitable for different diffuser types with high accuracy. It provides the theoretical and experimental basis for the structural design and selection of diffusers for heat storage tanks.
Subject
Energy (miscellaneous),Energy Engineering and Power Technology,Renewable Energy, Sustainability and the Environment,Electrical and Electronic Engineering,Control and Optimization,Engineering (miscellaneous),Building and Construction