Masaki Nakao

An efficient cooling system for telecommunication equipment rooms

The evaluation of air-flow systems for telecommunication equipment rooms was carried out experimentally. Parameters were room air temperature distribution and ambient temperature of electric parts, i.e. air temperature around circuit boards, which are influenced by an air-flow system. The under-floor air supply and overhead return system has shown to be superior to other flow systems and its allowable average heat density was up to 1.1 kW/m/sup 2/. A microcomputer control unit was developed for the cooling unit. It is shown that this control can optimize the refrigeration cycle of the cooling unit under low outdoor air temperature, minimizing running costs.<<ETX>>

Energy reduction in a telecommunications building using a cogeneration system

This paper describes methods of selecting the capacities of energy saving equipment for use in CGS (cogeneration systems) and other systems in a hypothetical building that is assumed to contain a mixture of telecommunications equipment rooms (TER) and ordinary offices, and the reductions in the amounts of energy consumed when such systems are employed. It has been done by (1) changing the proportion of the floor area occupied by the TER and the offices in the building that was used as the subject of our experiments, (2) converting the commercial electric source and town gas consumed at a given proportion into primary energy so that an identical criterion could be obtained for the purpose of making comparisons, and (3) comparing the reductions in energy consumed by the capacity of the equipment selected for use in the case being studied. In the base system, town gas was assumed to be the energy source for double-effect absorption chiller and a boiler used to cool and heat the offices and for packaged variable-air-volume system used to cool the TER. In addition, a gas engine was assumed to be the energy source for the CGS in a system in which the TER are cooled by single-effect absorption chiller driven by the exhaust heat from the engine. It was possible to determine the capacity at which effective utilization could be achieved throughout the year for cooling and heating by means of the exhaust-heat-driven single effect absorption chiller.

Humidity Control in a Containerized Station

When the compressor of a packaged air-conditioner for cooling a containerized station stops operating, the relative humidity of the room exceeds the upper limit of the specified range. The high relative humidity phenomenon is caused by water forming on the cooling coil of the air-conditioner. This water condenses, while the compressor is running, and is vaporized by the fan airflow which continuously operates, even after the compressor stops operating. As a result of this the water is not expelled to the outside but remains in the room, and the relative humidity increases. Several experiments are conducted to find a way of reducing the relative humidity in containerized stations. One way involves reducing the draft air volume, which contains a high level of moisture. Experiments and field tests indicated that the most effective method for maintaining the specified temperature range and relative humidity in a room, is to control the compressor by the room air temperature and the room fan by the relative humidity when the compressor stops operating.