政秀 金

The present paper proposes an optimal operational strategy for an actual HVAC system with a seasonal underground thermal storage system using a simulation technique. The simulation is a powerful tool for the system because it is difficult to try various operational methods experimentally in the actual system because of the long heat transfer time underground. This paper develops the whole system simulation by connecting an underground thermal model, which can simulate the heat exchange between the ground and the pipes buried in the foundation piles, with models of mechanical components in the air-conditioning system. Case studies about the operational method of the system are conducted using the simulation. The optimum operational strategy found using the simulation, which is to minimize the energy consumption of the whole system, can reduce energy consumption by approximately 12% (30.2 GJ to 26.5 GJ) and improve system efficiency from 3.61 to 7.14 as compared with the values of the present operational method.

Recently, corresponding to a diversification of educational contents and methods in school education, the number of schools which adopt an open-plan is increasing. But, there are a few study cases which reveal a characteristic of open-plan from the perspective of environmental engineering. In this study, the actual effects of natural ventilation windows on thermal environment and indoor air quality at classrooms are figured out from the field survey of thermal environment, indoor air quality and usage of classrooms .The result of the study, it was known that the rate of windows open is related to weather, wind velocity and outdoor air temperature. Furthermore, it was confirmed that natural ventilation windows control air volume from pressure difference, and enough amount of ventilation was available.

An evaluation was made to a system which stores low temperature natural energy of winter into the underground of building, and uses the energy for air-conditioning in summer. This is an innovative seasonal thermal storage system which is cost effective by avoiding additional piping work for the heat exchange by embedding pipes in structural pile foundations. Also, by simulating continuously from design phase to operation phase, verification and optimization of the system is conducted. In this study, main purpose of developing the system, beforehand forecast of the system performance by simulating, design plan of ground thermal storage HVAC system and evaluation of initial performance are reported.