Cooling operation characteristics of multi-A/C(air conditioner)s were experimentally investigated for combination of indoor units (A+B, A+C, B+C) and operating conditions (standard, overload, low temperature and low temperature freezing). The operating data and performance of the air conditioner were measured using a multi-calorimeter. We also observed compressor frequency and pressure variations. From the experimental results, it was found that the cooling performance and the operating characteristics depend on operation combination of indoor units, in the case of 2 room simultaneous operation. In the four types of cooling tests, the cooling capacity and COP of the 3 room simultaneous operation and 2 room simultaneous operation were similar. Through this experimental study, data on the simultaneous operation characteristics of 2 room simultaneous operation according to the changes of indoor and outdoor temperature of four kinds were obtained.

The cooling operating characteristics of the 3 room air conditioner are experimentally investigated for the number of the indoor units (A, B, C) and the operating conditions (standard, overload) under the cooling operation. The cooling capacity and COP were calculated using a multi-type calorimeter. Also, EEV opening, compressor frequency, and superheat degree were obtained when the compressor started. From the experimental results, we can see that the performance and operation characteristics of the air conditioner depend on the indoor unit operation method. In case of simultaneous and single operation, the cooling overload performance was measured lower than the standard condition. Also, in the overload operation, the power consumption of the compressor was greatly increased and the COP was also decreased.

A Blast valve is the device that is used in the air intake and the exhaust vent of CBRN(Chemical, Biological, Radiological and Nuclear warfare) protection facility. The valve is automatically closed when explosion pressure is applied from the outside of equipment. This study is investigated on the structural design and the performance of blast valve. After modeling the entire of blast valve and spring assembly, the data for the spring parameter is obtained through the finite element method and the operating limits of the valve are derived. Also, a prototype is made to determine the relationship between the load and the opening closing amount of valve through the load cell test. The performance of prototype at analysis as blast valve is agreed well with that at experiment. It is verified that the blast valve proposed in this paper is designed with the structure to endure the explosion pressure.