A district heating and cooling system that generates and supplies heat multiple buildings in an area is an effective measure for energy conservation in commercial buildings. However, a complicated situation arises when plants are constructed sequentially as buildings are developed. In such cases, the potential for efficiency improvement of whole system by heat interchange between plants is promising. Because heat interchange is expected to increase the pump power, it is necessary to understand the operating behavior of the plants. This study proposes an efficient operation method of heat interchange in a district heating and cooling system with two plants through simulation. First, we developed a detailed simulation program. The program considered pressure distribution of the piping system; therefore, it allowed theoretical calculation of pump power. By using this simulation model, we proposed a matrix of control set values that effectively executes heat interchange. The control set values included the direction and amount of heat interchange. The matrix is expected to enable operating managers to implement heat interchange appropriately in various operating situations.

In Japan, the concentration of airborne particulate matter in rooms must be maintained at 0.15 mg/m³ according to the Building Sanitary Law, a photometer is generally used to measure the concentration. However, it is necessary to calibrate the sensitivity of photometers: generally stearic acid particles of 0.3 µm diameter are used to calibrate them. Nevertheless, these particles seem unsuitable for calibration as they exist in a mono-dispersed state and are too small in size. This study verifies the applicability of Arizona dust and Kanto loam, wherein the stearic acid particles have a diameter of 1.0 µm, for the calibration of photometers. Moreover, we practically operated the calibrated photometers to investigate their characteristics. The results are as follows; 1) the indicated value does not agree with the concentration if the stearic acid particles has a diameter of 1.0µm, 2) variance of the indicated value is too large and the indicated value does not agree with the real concentration if the Arizona Dust is used as calibration particle, 3) variance of the indicated value is considerably small and it agrees with the real concentration if Kanto Loam is used as the calibration particle.