| The development and research of solar energy and phase change materials(PCMs) are the new directions in energy-saving field. The Trombe wall is a crucial technology in gathering and accumulating solar energy. It is a significant component in realizing the integration process of buildings with solar energy, which has been the common concern and research subject of international researchers in recent years. The thermal performance of Trombe wall exerts great important influences on the heating effect of passive solar house in winter. The paper employed both theoretical analysis and numerical simulation methods, carried study on the heat-transfer process of Trombe wall.The paper elaborated the basic theory of heat-transfer process of Trombe wall, built the mathematical model of a passive solar house with Trombe wall in Nanjing. The thermal equilibrium equations of Trombe wall system and interior architecture and simultaneous equations of flow and heat-transfer processes of the air in the gap were established through thermal balance analyzing of Trombe wall system and interior architecture. The paper compared simulation results carried out by the built model with research data of other literature, the outcome of which verified the validity of the turbulence model and DO model the paper had chosen. By using numerical simulation software, this paper conducted numerical simulations for temperature and velocity fields of major components of Trombe wall system, daily changes of thermal performance of Trombe wall and indoor thermal comfort indexes-PMV and PPD under winter condition. The paper also represented the temperature field of Trombe wall, velocity field of the air gap, temperature and velocity distributions of air at the upper vent, temperature field for different hours of Trombe wall and the velocity distribution of the air in the gap, compared the heating performance, PMV and PPD of Trombe wall system with general building when there were no auxiliary heat sources while other conditions were same, which verified the superiority of Trombe wall system over general building, and made analysis of the distribution laws of the temperature and velocity fields inside Trombe wall system.In addition, based on sustainable development and energy conservation, the paper made comparative analysis on the influence of different PCMs, wall thicknesses, the center distances between the upper and lower vents, vent areas, the thicknesses of air gap on the thermal performance of Trombe wall system by numerical simulation, then optimized the design for Trombe wall system, making it accord with the people-oriented philosophy. The results of comparative analysis showed that when selecting PCMs, besides the consideration of heating load, the service life and other aspects of PCMs should also be taken into account. The heating load of Trombe wall system integrated with PCM whose phase change temperature is 49℃ and transformation latent heat is 213kJ/kg changes slowly with time, and can meet the heat demand of the room. When the system adopts the aerated concrete block filler wall with the thickness of 200mm or 250mm, the thermal efficiency is relatively high and the phenomenon of heat back-flow weakens, the aerated concrete block filler wall with the thickness of 150mm is not recommended. The center distance between the upper and lower vents should be increased as long as condition allows, thus increasing the heating load from Trombe wall system to indoor environment. When the vent area is 1%-2% of the wall area, the total heating load of Trombe wall system is the biggest. Either the over-size or under-size of the thickness of the air gap, the systems will lose heat to the outside environment, so the suitable thickness of the air gap is between 50mm and 100mm. The research results of this paper can serve as reference for the design of major components of Trombe wall systems in Eastern China. |
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