Determination of Heat Losses from the Pipeline in SDHW System during the Continuous Change of the Supply Temperature

Miroslaw Zukowski

doi:10.3390/en14010090

Abstract

In this article, the research object is the solar domestic hot water (SDHW) heating system that has been in operation since 2015 and is located on the campus of the Bialystok University of Technology (Poland). The thermal performance of solar collectors are thoroughly investigated so far. Therefore, special attention was paid to the issue of the heat loss from pipes. The measurements showed that the heat transfer in circulation pipes is quite complex due to continuous fluctuations in water temperature at the supply of this loop. As it turned out, the application of the classical method of energy balancing and the readings from heat meters gave inaccurate results in this case. The main aim of this study was to develop a different approach to solving the problem of determination of heat losses. The method presented in this article is based on computational fluid dynamics (CFD) and measurement results as the input data. The practical result of this study was the development of two relationships for calculating the heat loss from pipes. A separate issue, that is discussed in this paper, concerns the impact of the time intervals used in numerical simulations on the accuracy of calculation results.

Highlights

Solar thermal technologies are widely used in small and medium scale in single-family, multi-family, hospitals, public, and office buildings
Domestic hot water (DHW) heating systems supported by flat plate or evacuated tube solar collectors are most commonly used in Europe and China
Improvements should be sought within another field that offers potential opportunities for increasing the energy efficiency of the solar installations

Summary

Introduction

Solar thermal technologies are widely used in small and medium scale in single-family, multi-family, hospitals, public, and office buildings. The amount of converted solar radiation energy received directly by the final recipient depends on the efficiency of the designed system and climatic conditions. It usually covers between 30% and 50% of the energy demand for heating the tap water. Improvements should be sought within another field that offers potential opportunities for increasing the energy efficiency of the solar installations. One of these areas may be the reduction of heat loss from pipes connecting the system elements

Objectives

Methods

Conclusion