Energy performance and economic study of a solar floor heating system for a Hammam

Abstract

This paper deals with a numerical and experimental study of energy performance as well as an economic study of a solar under floor heating system for a traditional bathroom (Hammam). Prior to this, the solar under floor heating system was designed via a parametric study conducted by means of dynamic simulations for the solar collectors area and inclination, the storage tank, the piping materials, the pumps mass flow rates, the temperature regulation and the thickness of the active slab. Moreover, two configurations with or without thermal storage were compared. The Hammam was monitored via air temperature and humidity measurements as well as IR thermography. Good agreement between simulation and experimental results was found with 94% of the discrepancies less than 1°C. Numerical results show that the system without thermal storage allows the Hammam's operative temperature to reach the desired one. The latter ranges between 30°C and 37°C for sunny days in winter, while the system with thermal storage leads to at least 10°C operative temperature lower compared to system without thermal storage. In addition, the thermal storage system allows having quasi-constant floor temperature that depends on the storage volume, as it avoids large day/night temperature fluctuations thanks to its thermal inertia. Nevertheless, the solar floor heating system configuration with storage tank does not achieve the desired floor surface temperature of the Hammam. Furthermore, it was stated that the best configuration, which leads to an operative temperature of around 35°C inside the Hammam, is that with cross-linked polyethylene serpentine tubes (PEX) inserted in a concrete slab of 5cm thickness, 4m2 water solar collectors with 80kgh−1 mass flow rate and temperature regulation difference of 5°C. On the other hand, the studied solar floor heating system exhibits high to excellent energy performance depending on the use of the Hammam and auxiliary heating is almost not needed for a rational use. Furthermore, the economic feasibility of the solar floor heating system of the Hammam indicates that the annual heating energy consumption is reduced by at least 72%. Moreover, the annual energy savings are about 950 MAD (around 97 USD) and 690 MAD (around 70 USD) respectively compared to the electric and gas heating systems. The payback period of the solar system is then around 6 and 8 years respectively. Over the lifetime of the solar system, which is assumed to be 15 years, its cumulative reduction of the CO2 emissions is up to 10 tons.