Abstract
This paper describes a study on the evaluation of the reduction in energy consumption on various air conditioning systems. Four air conditioning systems are chosen: single duct constant air volume system, single duct variable air volume system, terminal reheat system and dual duct system. The annual heat consumption is determined quantitatively by the computer simulation for each system. It was found that the deficient heat and excess heat amounted to 20〜85% of the total heat extraction rate of a room depending on the air conditioning system and could be regarded as the indexes, which indicates follow-up ability to maintain the room temperature. The factors affecting the annual heat consumption could be identified as follows; (1) zoning, (2) the method used in determining the flow rate and the temperature control, (3) the method of inducing the outside air, (4) the setting of the room thermostat. The annual heat consumption at the air handling unit were calculated taking these factors into consideration for 26 cases, where coil arrangements, control of coil performance, setting of supply air temperature, outside air intake, etc. are varied. (1) Large differences are shown between the systemes with zoning and with out zoning. For example, terminal reheat system with out zoning consumed 2.3 times more heat for cooling, 2.6 times more for heating, than constant air volume system with zoning. These excess energy in required due to the reheat losses and mixing losses which varies according to the zoning. (2) Heat consumptions which consumed at the reheat coil to maintain the air humidity in the room are in high volume. For example, reheat system consumes 85% more heat volume than the single coil system, to maintain the room air humidity. (3) Heat consumption varies very much according to the location of the room thermostat. In the case of this study, heat consumption increased 11% under the influence of unsuitable location of the room thermostat. (4) The heat consumption of the system, which induced the outside air in proportion to the drybulb temperature, decreased by 8.5% in cooling and increased by 24% in heating. This increase is produced by humidifying load. But the heat consumption of the system, which induced the outside air in proportion to the enthalopy, decreased by 6.1% in cooling and 1.2% in heating. The heat consumption of the system with total heat exchanger decreased by 7.7% in cooling and 39.8% in heating.
