Effects of operating conditions and device's geometrical sizes on geometrical properties of wall-attaching transonic jet between two parallel plat plates are numerically simulated. Conclusions are as follows: 1) U...Effects of operating conditions and device's geometrical sizes on geometrical properties of wall-attaching transonic jet between two parallel plat plates are numerically simulated. Conclusions are as follows: 1) Upriver part of the wall-attaching jet's center streamline is in good accordance with parabola; 2) When both gas inlet pressure and outlet pressure as well as their ratio are not too high ( the outlet pressure is less than 10 MPa and the pressure ratio is less than 3), the center streamlines of the wall-attaching jet with the same pressure ratio coincide with each other very well, and the deflection degree of the center streamline decreases with rise of the pressure ratio; 3) The deflection degree of the jet's center streamline decreases with either broadening of nozzle's throat or rise of wall offset; 4) With rise of the pressure ratio, attachment distance of the jet increases, but the increase rate descends; 5) The attachment distance ascends with rise of either the nozzle's throat or the wall offset.展开更多
Night ventilation is regarded as a promising cooling strategy by storing night cooling in the thermal mass of the building.However,night ventilation performance in hot summer is restricted by the climatic limits.In th...Night ventilation is regarded as a promising cooling strategy by storing night cooling in the thermal mass of the building.However,night ventilation performance in hot summer is restricted by the climatic limits.In this paper,we propose a new solution as the integration of wall-attached night ventilation(WANV)and phase change material wallboard(PCMW).The principle of the proposed system is to utilize the wall-attached jet ventilation to achieve forced convection and to adopt latent energy storage of PCMW to enlarge the energy storage density capabilities,and the coupling method is expected to improve the night ventilation performance.Comparative experiments were conducted to evaluate the thermal performance of the hybrid system by evaluating indoor temperature history,thermal comfort time and cooling efficiency.Due to the high thermal energy storage density capability of PCMW,it was found that the presence of PCMW has a negative influence on night cooling efficiency but still has a positive influence on the overall cooling effect.The proposed WANV combined with the PCMW system significantly increased the temperature decrease of room air and west wall inside surface during one hour's night ventilation by 94.97%and 67.74%,respectively,and reached an extension of 38.42%of indoor thermal comfort time.The results highlight the potential of WANV integration of PCMW to improve the thermal performance of night ventilation.展开更多
基金Chinese 863 National Program Foundation(No.2006AA05Z216)
文摘Effects of operating conditions and device's geometrical sizes on geometrical properties of wall-attaching transonic jet between two parallel plat plates are numerically simulated. Conclusions are as follows: 1) Upriver part of the wall-attaching jet's center streamline is in good accordance with parabola; 2) When both gas inlet pressure and outlet pressure as well as their ratio are not too high ( the outlet pressure is less than 10 MPa and the pressure ratio is less than 3), the center streamlines of the wall-attaching jet with the same pressure ratio coincide with each other very well, and the deflection degree of the center streamline decreases with rise of the pressure ratio; 3) The deflection degree of the jet's center streamline decreases with either broadening of nozzle's throat or rise of wall offset; 4) With rise of the pressure ratio, attachment distance of the jet increases, but the increase rate descends; 5) The attachment distance ascends with rise of either the nozzle's throat or the wall offset.
基金the financial support of the National Key Research and Development Program of China(Grant No.2018YFC0705306)National Natural Science Foundation of China(No.52108096)+1 种基金Fundamental Research Funds for the Central Universities(No.2682020CX28)project from Key Lab.of Marine Power Engineering and Tech.authorized by MOT(No.KLMPET2020-04)。
文摘Night ventilation is regarded as a promising cooling strategy by storing night cooling in the thermal mass of the building.However,night ventilation performance in hot summer is restricted by the climatic limits.In this paper,we propose a new solution as the integration of wall-attached night ventilation(WANV)and phase change material wallboard(PCMW).The principle of the proposed system is to utilize the wall-attached jet ventilation to achieve forced convection and to adopt latent energy storage of PCMW to enlarge the energy storage density capabilities,and the coupling method is expected to improve the night ventilation performance.Comparative experiments were conducted to evaluate the thermal performance of the hybrid system by evaluating indoor temperature history,thermal comfort time and cooling efficiency.Due to the high thermal energy storage density capability of PCMW,it was found that the presence of PCMW has a negative influence on night cooling efficiency but still has a positive influence on the overall cooling effect.The proposed WANV combined with the PCMW system significantly increased the temperature decrease of room air and west wall inside surface during one hour's night ventilation by 94.97%and 67.74%,respectively,and reached an extension of 38.42%of indoor thermal comfort time.The results highlight the potential of WANV integration of PCMW to improve the thermal performance of night ventilation.
