NUMERICAL STUDY OF THE EFFECT OF STORAGE TANK STRATIFICATION IN SOLAR DOMESTIC HOT WATER SYSTEMS |
Paper ID : 1326-ICESE |
Authors: |
Mehrdad Shirinbakhsh1, Nima Mirkhani2, Behrang Sajadi *3 1Department of Mechanical Engineering, KNT University of Technology, Iran 2Department of Mechanical Engineering, College of Engineering, University of Tehran, Iran, 3Department of Mechanical Engineering, College of Engineering, University of Tehran, North Kargar St., Tehran, Iran |
Abstract: |
In this paper, performance of a conventional solar domestic hot water system is modeled. These systems typically are capable of providing 50 to 70 percent of annual hot water energy demand. Solar fraction of such systems is influenced by several key parameters such as the collector efficiency and the storage characteristics. By modeling the solar irradiation, the available useful energy from the collector may be calculated. Then the governing equations of the storage tank and the collector are coupled in order to simulate the overall performance of the system. The implemented program presents monthly average behavior of the system including the storage tank temperature profile and the solar fraction. Storage tank stratification may have a tangible effect on the operation characteristics. This effect is studied thoroughly in the context of the number of nodes; and the sufficient nodes number to model a fully stratified tank is obtained. In addition, the sensitivity analysis is conducted in order to study the collector area, the storage tank volume and its heat loss coefficient effects on the solar fraction. The results indicate that the storage tank temperature profile is strongly affected by demand profile and therefore the solar fraction could be enhanced by using other forms of energy storage such as phase change materials. On the other hand, stratification can increase the solar fraction up to 10% annually and 6 nodes are capable of describing a fully stratified tank. Furthermore, it is found out that annual solar fraction is most sensitive to the collector area around the design point as 10% variation of collector area leads to 7% change in the annual solar fraction. |
Keywords: |
Solar domestic hot water (SDHW), Storage tank, Stratification, Mutli-node, Numerical simulation |
Status : Paper Accepted |