## THERMAL SCIENCE

International Scientific Journal

### Thermal Science - Online First

online first only
### Entropy generation analysis and thermal characteristics of radiation heating system

**ABSTRACT**

This article presents the developed methodology for the numerical simulation of radiation heat transfer from water panel heaters and optimization results of water temperature in the supply pipeline from the mass flow rate of the heat-carrier and the surface area for a given thermal power of the panel system. A numerical mathematical model is developed in the assumption that heat transfer occurs by means of radiation heat exchange by longitudinal ribs and pipes, which are thermally insulated on top. It is assumed that the temperature of the rib base is equal to the temperature of the outer wall of the pipe. The irregularity of the radiation density in different directions depends on the angle and distance to the irradiated area. The aim of the work is to develop a methodology to simulate the heat transfer processes of a radiation panel water heating system and optimization of design and operating parameters. The radiation intensity is determined by a numerical method using the MATLsoftware package. Our results of experimental studies of the radiation flux density are presented and compared with the results of numerical ones. The thermodynamic efficiency of a panel heating system is analyzed using the entropy production method (exergy destruction). The multicriteria optimization of water temperature in the supply pipeline is performed by LPτ-search. It is found that the unevenness of surface temperature of panels reaches 24.4% as well as for the panels of about 50m in length a decrease in water temperature to 20K is observed, which leads to the unevenness of radiation flux density over the heated area. The area of the cooling system as a function of water temperature and the conditions under which the entropy production in the system is minimal is determined.

**KEYWORDS**

PAPER SUBMITTED: 2019-02-16

PAPER REVISED: 2019-08-16

PAPER ACCEPTED: 2019-08-28

PUBLISHED ONLINE: 2019-09-15

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