Study On Basic Theory Of Thermosyphon-Embedded Floor Radiant Heating

Thermosyphon-embedded floor radiant heating is a novel heating system with high efficiency, low energy consumption, and beneficial to protect environment. There were few related reports on study and application of this new radiant heating system not only in domestic but also in foreign; therefore, a serial systematic and comprehensive study on thermosyphon-embedded floor radiant heating was expanded in this dissertation. The main work and results are listed as follows.1. Experimental investigation on thermal performance of series-wound thermosyphonsThermal performance of series-wound thermosyphons to be used in floor radiant heating was tested. Experimental results indicated that: when applied in low-temperature floor radiant heating, the optimal working condition of series-wound thermosyphon is the inclination angle of 1~2?, series-wound type of D, and evaporative length of 110mm. Meanwhile, experience formulas for the calculation of heat transfer rate and surface temperature of single thermosyphon were fitted by a plenty of test data.2. Establishment of the quasi-tridimensional unsteady heat transfer model of thermosyphon-embedded floor and analysis of heat transfer performance of thermosyphon-embedded floori) According to heat transfer process in thermosyphon-embedded floor, the quasi-tridimensional unsteady heat transfer model of thermosyphon-embedded floor was set up, and numerically solved by finite volume method. ii) Numerical results for thermosyphon-embedded floors with different structures indicated that surface temperature and heat transfer rate of floor are increased with the rising of hot water temperature, rising of water flow rate, decreasing of thermosyphon distance, decreasing of packed layer thickness, rising of surface material heat conductivity, while little surface material heat conductivity and great thermosyphon distance make thermal storage performance of thermosyphon-embedded floor better. iii) Heat transfer efficiency of thermosyphon-embedded floor is higher than that of PPR pipe embedded floor, so that the supply temperature of hot water for thermosyphon-embedded floor radiant heating can be reduced by 4~6℃. iv) Thermal storage performance of thermosyphon-embedded floor is better than that of PPR pipe embedded floor, because surface temperature of thermosyphon-embedded floor increases quickly and decreases slowly.