The global demand for energy conservation and the mitigation of the effects of global warming requires a reliable performance assessment of the many air conditioning installations operating in commercial and residential buildings worldwide. Current JIS performance evaluation procedures for air conditioners are performed at a fixed compressor speed while deactivating the native control system. It has been pointed out that these tests are not representative of the actual performance of air conditioners, which dynamically respond to thermal loads with variable or cyclic modulations of the compressor speed and expansion valve opening according to the native control system. Therefore, this study establishes a new "emulator-type” load-based performance evaluation methodology for evaluating the actual performance of air conditioners. The methodology consists of a software that can arbitrarily simulate the building side load-environment, and a testing facility for the measurement of the system performance based on the air-enthalpy method. The integrity of the testing facility is confirmed and tests are conducted for different load conditions and different room sizes. It is demonstrated that the proposed methodology can reproducibly evaluate both steadystate and dynamic performance of air conditioners operated while using their native control system.

A compressor rupture accident may occur because of erroneous operation during the pump-down of residential split air conditioners. An engine for a model airplane was used to simulate a refrigerant compressor, and experiments were conducted on the diesel combustion of mixtures of refrigeration oil, refrigerant, and air. The effect of the reaction inhibitor concentration in the refrigeration oil on combustion suppression was investigated. The refrigeration base oil was polyol ester, and four additives were used. The refrigerants used were R 22, R 32, R 1234yf, and R 290. The combustion range became narrower, and the maximum pressure decreased as the concentration of the additive increased. Additive A4 showed a suppression effect on many refrigerants even when one wt% was added. In particular, for R 290 and R 1234yf, the concentration range of diesel explosions was significantly reduced.

With the growing momentum to prevent global warming, the development of refrigerants with high efficiency and low global warming potential (GWP) has become an urgent issue, and many substances have been proposed as candidates for next generation refrigerants. The equation of state (EOS) is formulated by the accurate measured thermophysical properties. The measured speed of sound is one of the induced state quantities that used to confirm the thermodynamic consistency of the obtained EOS. In this work, we report the results of the speed of sound measurement in liquid phase by using commercially available equipment. The speed of sound in the liquid phase of R1233zd(E) and R1224yd(Z) were measured by a pulsed ultrasonic sensor. Using the existing EOS for water and R1336mzz(Z) as a reference, and applying a compensation for the effects of pressure and sonic absorption, we have succeeded in obtaining accurate speed of sound values that can be used to EOS formulation.

This study verifies the effect of temperature and humidity environment on vegetables freshness in long-term storage. The time-course changes in the freshness indices of vegetables, including appearance, water content, nutrient content and taste by taste sensing system, were evaluated after storing the vegetables in the refrigerator using the secondary refrigerant (hereinafter referred to as the “brine type refrigerator”) capable of maintaining low temperature and humid environment and the generic direct expansion type refrigerator for several months. " The results showed that significant appearance deterioration such as wilting and discoloration of the carrots stored in the brine type refrigerator were inhibited, and there was a significant difference in bitterness and astringency increase about 90 days storage compared to those stored in the direct expansion type refrigerator. The cabbages were also found to inhibit deterioration in appearance due to yellowing and rotting, and there was a significant difference in the time-course vitamin C loss compared to those stored in the direct expansion type refrigerator.