Cooling water subsystems, which consist of water-cooled chillers, cooling towers, and cooling water pumps, have been studied for efficient operation. On the other hand, the cooling tower, which constitutes the cooling water subsystem, is highly affected by external disturbances. Deviations between desk studies like simulations and the actual system tend to be larger than for other equipment. Therefore, we used system simulation to understand the extent to which power consumption is affected by the presence of sensor errors and errors in the accuracy of the simulation model. In addition, we compared the cooling tower fan control method between control based on the cooling water temperature and control based on the cooling tower fan frequency and quantitatively evaluated the differences.

The purpose of this study is to develop a heat recovery ground source heat pump (HR-GSHP) system that is expected to be installed in large complex buildings, factories, and multiple buildings where heating and cooling loads simultaneously generate. As Part1 of the study, a design method for HR-GSHP systems were established by applying the optimization method. First, the authors explained the modeling of temperature change of the ground and thermal medium in the ground heat exchanger, and a method to distribute the thermal load of each ground source heat pump unit in the HR-GSHP system using optimization methods. In addition, it was assumed that the HR-GSHP system with 100 m x 40 borehole single U-tube ground heat exchangers was installed in a food factory and the thermal load for each ground source heat pump unit was distributed by applying the optimization method. Then, a simulation of HR-GSHP system operation were carried out by using the distributed thermal loads. The results showed that the maximum heat injection rate of the ground heat exchanger was about 60 W/m and the heat maximum extraction rate was about 54 W/m. It was confirmed that repetitive heat extraction and heat injection increase the heat extraction rate and the heat injection rate of the ground heat exchanger. Furthermore, the cost payback period of the HR-GSHP system was estimated to be 7.2 years, which is much shorter than that of conventional ground source heat pump systems.

“Manhole toilets” are available for use during disasters. Generally, manhole toilets connected to sewerage conduct require water sources and supply means to transport human waste. Although efforts are being made in apartment buildings to stockpile manhole toilets for use on soil chamber, it is necessary to use a vacuum truck to pump out the human waste without water sources and supply means. Additionally, at the restoration of the water supply system, there is a risk that the wastewater will not be transported due to the inverts being blocked by the human waste. In order to avoid the invert blockage, we developed a soil chamber excrement-catcher for manhole toilets. The developed device targets 600 Φ soil chambers and is capable of capturing excrement 50 times a day, i.e. 350 times a week. It was demonstrated that the excrement can be washed into the sewerage using a household high-pressure washer after the water supply restoration.