| Title |
Study on Energy Consumption Model and Long Term Energy Conservation Effect of Hybrid Air Conditioning System based on Natural and Mechanical Ventilation |
| Keywords |
Natural Ventilation ; Hybrid Air-conditioning System ; Dynamic Load Calculation ; System Simulation |
| Abstract |
Hybrid air-conditioning system utilizing natural ventilation and mechanical air-conditioning systems is expected to improve the quality of the indoor thermal and air environment and to reduce energy consumption. In the paper [1] and [2], the characteristics of the indoor thermal environment of hybrid air-conditioning system utilizing natural and mechanical ventilation were examined with CFD(Computational Fluid Dynamics) simulation under the various conditions of outdoor air, mechanical air-conditioning system, indoor heat generation rates and the width of office room. Also, cooling load of the mechanical air-conditioning system to maintain the task zone at the target temperature (26C) was analyzed based on the results of these simulations. From the results of case studies, a simple cooling load model implying energy conservation effect of hybrid air-conditioning system was proposed in this study. The point of this cooling load model is that the temperature stratification in a room is considered in building energy simulation (net work simulation) for long term. This characteristic of the model is different from the existent load model which regards indoor space as a single node and, by that, is supposed perfect mixing. The temperature stratification in a roon was reflected into the load model by modeling exhaust air temperature which was decided by the conditions of incoming outdoor air temperature, flow rates and indoor heat generation rates. The accuracy of the cooling load model was investigated by comparing with the results of CFD simulation and was evaluated to have a approximate 10% error. By utilizing the cooling load model evaluated in this study, energy simulation for the office building of 25 stories was conducted. HASP/ACLD was utilized for the dynamic cooling load calculation and the results of load calculation was modified by the simple cooling load model of hybrid air-conditioning system proposed in this study. Long term energy simulation was conducted by utilizing HASP/ACSS. The results show that energy conservation rate of 16% was achieved and natural ventilation was avaliable for an approximate 44% of cooling times. |