In Japan, since 2011, risk assessments of various appliances had been carried out to establish methods for ensuring the safe use of products using A2L refrigerants, followed by product launches in Japanese market. However, further shift to lower GWP refrigerants is desired in response to the Kigali Amendment. Most of the refrigerants with low GWP are A3 refrigerants with a small LFL and high flammability. Therefore, the Japan Refrigeration and Air Conditioning Industry Association have been carried out the risk assessments of built-in refrigerated display cabinets using A3 refrigerants. The calculation method that can accurately calculate the ignition probability for A3 refrigerants is proposed in this paper. And, the refrigerant leak analysis carried out to quantify the flammable space, the details of the risk assessment and established Japanese standards are explained.

Calcium maltobionate is expected to be an effective food material because of its high water-solubility, high calcium-bioavailability, and mildly bitter taste. However, little has been reported about the effect of calcium maltobionate on the physical properties of food. The purpose of this study was to clarify the effect of calcium maltobionate on the retrogradation of cooked rice in chilled storage. The compressive force and re-gelatinization enthalpy of non-additive sample increased with increase in storage time because of the progress of retrogradation. The compressive force and re-gelatinization enthalpy were diminished by the addition of calcium maltobionate because calcium maltobionate prevented the retrogradation of starch. The effect of calcium maltobionate on the retrogradation of starch will be originated from the hydrogen bonding formation of maltobionic acid and the electrostatic interaction of calcium ion.

"Freezer burn" is a type of quality degradation that occurs in frozen foods during frozen storage, which includes drying, degeneration, and discoloration. It is considered to be a sublimation phenomenon caused by a change in water vapor pressure due to temperature variations; however, there have been no studies regarding freezer burn in frozen pasta. In this study, the development of freezer burn in frozen pasta was visually monitored using a cryo synchrotron radiation X-ray computed tomography method. Using this approach, the state of freezer burn in the pasta was successfully visualized without sample pretreatment. The study revealed that temperature changes during storage accelerated the loss of moisture in frozen pasta. This was enhanced by increasing the frequency and amplitude of the temperature change. These results strongly indicated that, in order to suppress freezer burn of frozen pasta, storage freezers must be designed to suppress temperature changes.

In the field of the absorption chillers with LiBr/H2O as its working pair, a small amount of absorbent was mixed in the evaporator to lower the freezing point of the refrigerant and obtain lower temperature output. The purpose of this study is to develop a middle-low temperature absorption chiller that provides 1 to 3 °C chilled water by applying the above method for general hot water-driven single-effect absorption chillers. As the fundamental step of the development, this paper discusses the behavior of the cycle by cycle simulation considering dilute solution in the evaporator. We have developed a cycle simulator that includes the physical and heat transfer characteristics of the dilute solution. “2-step evaporator and absorber” was taken into consideration that is adopted to improve the cooling efficiency. This simulator also draws a Dühring diagram that helps us to understand this cycle. In conclusion, we have found that this cycle has enough margin against refrigerant freezing and solution crystallization by setting appropriate LiBr concentrations in the evaporator. These results lead us to the conclusion that an absorption chiller with 1 to 3 °C output using dilute LiBr solution has sufficient feasibility to be put into practical use.

For the low-temperature waste heat utilization, we have developed a “middle-low temperature absorption chiller” that provides 1 to 3 °C chilled water to promote waste heat utilization. This chiller has almost the same structure as a present single-stage absorption chiller and uses LiBr/H₂O as its working pair. A small amount of absorbent (LiBr) is mixed in the evaporator to prevent the refrigerant from freezing. In this paper, we developed a production prototype as the practical use stage and verified the performance and behavior under the conditions of a 1 to 3 °C chilled water outlet. As a result of the experiments, the coefficient of performance (COP) was 0.71~0.73 by supplying 90 °C heat source hot water and 28 °C cooling water. The prototype operated successfully during the experiments without any problems such as refrigerant freezing or solution crystallization. We also computed the characteristics of the prototype using the cycle simulator with the same condition as the experiment. The simulation results agreed with the experimental results within ±5% for the cooling capacity and heat input and ±0.005 for the COP. Based on these results, we have put the “middle-low temperature absorption chiller” in practical use.

The objective of this study is to investigate the technological feasibility of heat transportation based on an ammonia absorption cycle named STA. STA recovers discharged steam from waste power generation to convert it into a cooling and heating supply. An optimization model was employed to analyze technological selection with the criteria of minimizing total system cost. The results indicate STA is adopted when the heat transportation distance is 3-6 km at maximum, which implies that heat utilization in addition to power generation is effective for waste incineration plants as well as for district heating systems.

A crossflow desiccant coated heat exchanger (CF-DCHE) driven by temperature swing adsorption based on direct hot water heating and evaporative cooling utilizing residual hot water was experimentally investigated. The time-averaged amount of dehumidification was examined as a key performance indicator while varying the primary operating parameters, including the cooling air velocity, process air velocity and regeneration/dehumidification cycle switching time. The results indicate that the adsorption outlet air humidity was decreased while the minimum humidity at the beginning of the adsorption period was decreased as the cooling air velocity was increased. After a certain period of time, the evaporation of water proceeded at a high rate and isothermal conditions were approached as adsorption progressed. The data also show that dehumidification performance was significantly affected by both the cooling air velocity and the cycle switching time. At shorter cycle switching times, the cooling air velocity had an effect on the time-averaged amount of dehumidification, but this phenomenon disappeared at longer cycle times under the present test conditions. When using the optimal switching time, the time-averaged amount of dehumidification increased along with the process air velocity in the case that cooling air was supplied.

With the increase in energy consumption, energy-saving attracts lots of attention. The desiccant dehumidification system is a potential substitute for the air-conditioning system that can achieve energy saving by decreasing the energy input for latent heat. Besides, the desiccant dehumidification system can further utilize the low-temperature heat waste in the desorption process. Thus, this study has focused on the low temperatures range between 40ºC and 70ºC on the desorption process with low humidity ratios of dry air as 0.005 kg/kg. The results indicate that, with the increasing desorption temperature, the water removal amount also increases, which means the ability of dry air to capture moisture from desiccant increases with higher temperature. At the desorption temperature of 68ºC, the average moisture removal capacity reached the peak, 0.0081kg/kg. Conversely, the coefficient of performance (COP) of the desorption process presented a downward trend with increasing desorption temperature. At desorption temperature 41ºC the COP is highest at almost 0.8, then gradually dropped to around 0.51 at desorption temperature 68ºC. The optimal desorption temperature can be determined as 54ºC.

The generation of steam with high temperate was investigated when saturated humid air is flowed into the adsorption heat pump used the packed bed with 13X zeolite. As a result of experiments to measure temperature of generated steam, its maximum value was over 150 °C when humid air was preheated to 70 °C. Since the maximum temperature of steam was not drastically affected by superficial velocity of humid air, it was presented that the maximum temperature does not depend on the heat transfer between humid air and zeolite under experimental conditions in this study. Hence, the maximum temperature of steam was estimated by the relationship between the adsorption equilibrium and heat balance under the assumption that both of temperature in gas and zeolite are equal. As a result, it was revealed that the maximum temperature was possible to be estimated by this method under the condition that the temperature of humid air is high.

Nanotailored microporous silica represents one of the more recent artificially prepared advanced materials used in heat transformation and conservation field after silica gel and various zeolite and zeolite-like materials. In this work, we introduce experimental findings on the energy characteristics of water adsorption on nanotailored microporous silica with 1.5 % aluminium doping in the structure. The downscaled system in this work simulates actual working conditions in a controlled environment for both heating and cooling mode. The key properties of this material lie in the regeneration temperatures 60 to 80 ℃ and COP, which reaches values around 0.6 in case of cooling and 0.7 in case of heating. In absolute values at ΔT = 15 ℃, the system reaches storing capacities of about 90 Wh and 126 Wh per adsorbent kilogram in terms of cooling and heating potential energy, respectively. An important factor of kinetic influence on system performance is discussed on a basis of constant time experiment and time-dependent energy flow breakthrough analysis. Constraining factors are found to be in parallel through the driving force of the pressure swing as well as the heat transfer through the body of the adsorption bed.

Water vapor adsorption on activated carbon (AC) for dehumidification purposes has gained much attention due to the abundance of benefits provided by AC. The working region limited in high water vapor relative pressure (P/P0) makes this material suitable only for removing water vapor at a highly humid region. In this study, ozone oxidation was conducted to introduce more oxygen-based functional groups on AC to attract more water molecules. Based on surface characterization results, ozone oxidation increases oxygen functional groups such as carboxylic on AC but decreases their pores. The more AC exposed to ozone, the more different properties could be observed. The increment of functional groups enhances the water vapor adsorption uptake at P/P0 ≤ 0.6, shifting the water sorption into lower P/P0.

The purpose of a heat transformer cycle is to extract heat at high temperature by utilizing waste heat at low temperature level. The heat generated during the adsorption of high-pressure water vapor raises the temperature of the external fluid to be used flowing in the adsorption reactor. However, since the heat input during preheating of the reactor and the heat removal during precooling are large, therefore, the heat capacity seems to affect the performance. In this study, first, thermodynamic analysis of the equilibrium cycle was performed to predict the amount of extracted heat from a low heat capacity reactor. The heat capacity was 20% smaller than that of the conventional reactor, and as a result, the output heat was 20% higher. Therefore, it was clarified that the decrease in heat capacity directly led to an increase in output heat. In addition to reducing the heat capacity, the effect of improving performance by heat recovery was also significant. The effect was almost the same as obtaining the upper limit of the output heat achieved by zeroing the heat capacity of the reactor. Moreover, from the viewpoint of exergy, heat recovery was important to enable high temperature extraction.