The ice adhesion force cannot be correctly measured using conventional macroscale methods because of the unevenness of the solid surface, especially, the metal surface. Thus, under a sufficient relative evenness of the copper surface to ice realized by forming nanoscale ice particles using a scanning probe microscope, the ice adhesion forces to the copper at various surface temperatures have been previously measured by one of the authors. Furthermore, reduction of the ice adhesion force to the copper surface at -5°C due to the addition of surfactant has also been previously realized. In the present study, ice adhesion forces to four types of metal with added surfactant were measured and compared with the results without surfactant. And validity of measured ice adhesion forces for four metals was clarified based on the adsorbed amounts of the surfactant molecules to four metals, the surface energies of ices with and without surfactant, and those of the metals.

Ice containing ozone micro-bubbles can be used for sterilization and deodorization, and is promising for the cold storage of fresh foods. In a previous report, considering concentration of ozone micro-bubbles fixed in ice formed by a batch system, it was clarified that even the ice kept −18 °C for 7 days had a sufficient sterilizing effect. Thus, as a first step for a practical application of generation of ice containing ozone micro-bubbles, the authors group developed a new continuous ice making system which has a nonconventional body feature. In this study, a plate ice containing ozone-micro bubbles was continuously generated using the developed system, and the concentrations of ozone micro bubbles in the ice maintained at −18 °C during 7 days and of ozone gas released from the melting ice were measured, respectively. And the relation equation between these two concentrations was clarified. Furthermore, for using a stable cooling efficiency of ice slurry the pseudo ice slurry consisting of a mixture of crushed ice and pure water was made, after which the relation between the melting time and the ozone water concentration of the pseudo ice slurry was clarified.

A growth prediction method depending on a cultivation condition is necessary for planning and operating vegetable production in a plant factory. This paper presented a growth prediction method based on plant physiology by expanding an air conditioning simulation tool developed by Komatsu et al (2014). The increase in leaf area, whose value was constant, was modeled as a growth curve and coupled with the photosynthetic rate. The photosynthetic rate equation was expanded by incorporating the dependency of the photosynthetic rate on CO2 concentration and wind speed. Because it found that water content was influenced by light intensity and wind speed, this effect was applied to conversion method from dry weight to fresh weight. The simulation method was validated by comparing the simulation results with the experimental results.

The subject of this study is to develop design and performance prediction tool for the ground source heat pump (GSHP) system with the variable water volume (VWV) in the primary side and the variable refrigerant flow (VRF) in the secondary side. The calculation models for the electric power consumptions of the water source VRF system and the circulation pump with VWV control were firstly explained. Next, the simulation tool, which was developed by applying the calculation models, were validated by comparing with the measurement data obtained by the field experiment. In addition, it was assumed that the GSHP system was installed in the middle scale hospital building that has the large variation of thermal load and the electric power consumptions for the GSHP systems were calculated. When the GSHP system with the VWV and the VRF was compared to the conventional GSHP system with the constant water volume in the primary side and secondary side, the reductions of electric power consumption for circulation pumps were 91% in the heating season and 92% in the cooling season, respectively.

The glass transition temperatures of the several kinds of materials which are considered to be effective as protective agents were measured before dry preservation experiment. The following four types of protective agents were selected to assess the dry-protective ability with Lactate Dehydrogenase (LDH); trehalose, trehalose with -Poly-L-Lysine (PLL) and trehalose with boron. The sample solutions of LDH with the various combinations of protective agents were rapidly vacuum-dried at the room temperature, followed by measuring their moisture content. After that, the dried samples were rehydration to measure the enzymatic activity by biochemical assay. The residual activity of LDH sample with trehalose was about 50% when its moisture content was 11 to 60 %. This dried-sample, however, suddenly lost its residual activity down to about 20 % when the moisture content decreased to 11 wt% or less. On the other hands, LDH samples with PLL alone and with trehalose + PLL kept their residual activities around 75 to 80 % in the wide range of moisture content. LDH samples with boron + trehalose kept their average residual activity from 69 to 74 %.

Two phase flow in micro channel has been of research interest recently due to its high heat and mass transfer rate, and in this study, experimental investigation is performed on the influence of wettability of the tube in slug flow. The liquid film thickness and flow behavior of water-air slug flow are investigated by using laser focus displacement meter (LFDM) and high-speed camera, respectively. Circular glass tubes with inner diameters of 0.76mm and 1mm are prepared to be hydrophilic or hydrophobic by applying surface chemical treatment (using chemical surfactant: piranha solution and toluene). The experimental results are compared and discussed to obtain the influence of wettability, and as a result, the liquid film thickness is found to be similar in hydrophobic and hydrophilic micro channels, which is compatible with theoretical analysis. However, the flow characteristics is influenced by wettability at low capillary number region, at which no liquid film exists. The critical capillary number for film deposition on the wall is influenced by the hydrophobicity of the tube, consequently, the critical capillary number is higher in a hydrophobic tube than that in hydrophilic one.

Heavy-duty diesel engines have been widely applied in commercial vehicles. However, escalating consumption of fossil fuels and stringent legislation of CO2 emission have raised the concern about searching for viable technologies to improve the fuel energy efficiency recently. Generally, optimization technology of engines can be categorized into two types: engine-powertrain-applied and engine-bottoming cycles. The bottoming organic Rankine cycle is an applicable combined heat and power (CHP) technology with great potential for engine waste heat recovery. The aim is to increase the fuel energy efficiency without additional fuel consumption. In this paper, a thermo-economic overview of organic Rankine cycle system integrated into engines especially for on-the-road vehicle is presented. First of all, characteristics of various engine waste heat (e.g. exhaust gas, EGR, CAC, jacket cooling water, oil circuit) are briefly analyzed; Afterwards, special attention is paid to the screening criteria of appropriate expansion machine and working fluid selection; Subsequently, an overview of various layout of organic Rankine cycle was presented; Eventually, cost-orient economic evaluation of the synthesis cycle is overviewed, which is meant for characterizing the optimum system design.

We investigated the energy consumption of heat source equipment in the university research facility building. The purpose is to clarify the current operation state of the heat source facility and propose a more efficient heat source facility system at the time of renewal. The survey method used BEMS data to calculate every hour of COP used by the heat pump of electric energy, inlet and outlet temperature and primary pump flow rate. As a result, the heat source efficiency of the heat pump had an the average COP=1.98 during cooling in 2016 and COP=1.98 during heating in 2016.The heat source efficiency at the time of designing the heat pump was COP=2.38 during cooling and COP=1.95 during heating. Therefore, it was revealed that the heat source efficiency average in 2016 was lower than the heat source efficiency at the time of designing the heat pump. Also, energy simulation of the target building was carried out and the energy consumption was estimated. As a result, we grasped the detailed energy consumption of the target building.

Drying air conditions of agricultural produce including the temperature and humidity affect the quality andappearance of the dried product. High temperature and higher humidity cause to loss of nutrient and color. Controlof the latent load of drying air prior to use for drying seems more effective approach for the preservation of delicateand temperature sensitive nutrient present in agricultural produce. Desiccant drying system (DDS) removes themoisture from the drying air and makes it possible to dry at low temperature and low humidity. In present study thepertinence of DDS with two desiccant materials LiCl and Silica gel were analyzed in order to find the optimumdrying conditions for wheat and rice. Results showed that in case of desiccant material LiCl, process airtemperature found higher and humidity lowers, thus provided more pressure deficit and speedup drying ascompared to the silica gel. The value of drying potential per watt also showed that desiccant material LiCl foundmore economical to use as compared to silica gel for all range of regeneration temperature. However for differenttype of grains, optimum ranges of regeneration temperatures is different i.e. 55-60ºC for wheat and 60-65ºC for rice.

In this study, we focused on the way of waste heat utilization to subcooling into refrigerated cabinets by cold heat of PCM (Phase Change Material) in the case of supermarket fields. On this experiment, we installed a heat exchanger into after the condenser of the refrigerated cabinet to control the subcooling degree using the PCM cold storage tank. The cold heat capacity of PCM tank water for subcooling was set assuming that it was supplied by adsorption refrigerator which was driven by the exhaust heat from gas engine and solar energy absorber. As a result, we confirmed that the power consumption decreased in the case of the refrigerated cabinet with subcooling contributed to CO2 emission reduction. Result of this experiment, the utilization of exhaust heat for subcooling by PCM was effective for energy conservation on the summer and the intermediate season. We confirmed, on the other hand, that the effect of subcooling by PCM could be disappeared when it was below 16 degree Celsius of the outside temperature.

This paper describes ground source heat pump (GSHP) that use direct expansion method. An underground heat exchanger consists of a copper pipe which is inserted directly into a foundation pile. We have carried out an experiment using the underground heat exchanger which inserted into the steel pipe pile. This paper describes the performance of the GSHP that use 15 sets of the foundation pile. Experimental apparatus is composed of a compressor, a four-way valve, an expansion valve, five indoor units and the underground heat exchanger. The underground heat exchanger is composed of steel pipe piles and copper pipes, and the foundation pile is filled with water. The heat exchanger is U-shaped with one and two pipes connected at the bottom part and is inserted into the foundation pile. The performance of GSHP system was evaluated by coefficient of performance (COP), which is determined by the ratio of the amount of exchanged heat to the power consumption of the compressor. From the experimental result obtained, the average COP exceeded 7 in the cooling mode. On the other hand, the average COP exceeded 5 in the heating mode. It was found that GSHP using direct expansion method which used the underground heat exchanger inserted in the foundation pile have high energy saving properties.

This paper analyzed life cycle costs of a ground source heat pump system used in a residence of Japan considering an advection effect of groundwater flow of eight different Darcy velocity. The required length of a single borehole heat exchanger was determined in each seven area of different heating/cooling loads to minimize the life cycle cost during 20 years through heat pump simulations. This study revealed that the effect of groundwater flow appeared when the velocity was more than 10 m/y and was almost converged when the velocity reached at 200 m/y. The cost decreased almost linearly according to the logarithms of the velocity. The velocity range was possible in steep valleys and alluvial fans of Japan. This study also showed that the costs were related mainly to the total loads, and secondarily to the groundwater flow conditions for the household system. Among seven areas, the household system was economically suitable relative to conventional air source heat pump systems in the cold areas 1 and 2 without initial cost reduction. The moderately warm areas 3 to 5 also became suitable when the initial costs would be reduced by 20 % as a common target of current R&D projects.

Recently, the installation of VRF (Variable Refrigerant Flow) heat pump systems in offices – regardless of their size and shape – has become popular in Japan. This system consists of a packaged outdoor unit and multiple indoor units connected by a refrigerant pipe. It has the advantage of fitting in easily with the any building plans because of its standardized system. Moreover, this system is energy saving and enhances user comfort, as it can be easily operated as an indoor unit. On the other hand, as there are infinite combination of indoor units of VRF systems available for the users to be chosen freely within the range of outdoor capacity, and since the indoor units can be turned on and off independently, operation conditions are not predictable. So it is very difficult to find adequate control parameters under wider load conditions. For this reason, the purpose of this paper is set to organize the control characteristics systematically. In order to evaluate VRF system, we develop a numerical simulation model based on the laws of physics. This model can easily add and delete indoor unit’s elements. Therefore, we hope that this model is adequate for VRF system’s analysis. In this report we reproduce machine’s operation conditions precisely; for example, for unstable condition, we reproduce the hunting phenomenon of expansion valve and evaluate the effects of different control constants under different loads.

In this paper, AQSOA-Z01, AQSOA-Z02, AQSOA-Z05 zeolites, CAU-10 and Aluminium Fumarate metal organic frameworks undergo N2 and water adsorption experiments to observe how variations of the material properties affect the water adsorption performances. The experimentally measured N2 isotherms data are used to calculate the BET surface area, pore volume and, most importantly, the pore size distribution of these adsorbent materials. The amount of water uptakes under static and dynamic conditions are measured by a thermo-gravimetric analyser, and these data are fitted with adsorption isotherms and kinetics models within acceptable uncertainties. Based on isotherms and kinetics data, the performances of adsorption cooling in terms of SCP (specific cooling capacity) and COP (coefficient of performances) are evaluated. It is shown the CAU-10 provides the highest SCP and COP as it has higher water uptake – offtake differences with fast kinetics.

In industrial fields, heat source over 130°C are widely needed, and for this development of industrial high-temperature heat pump systems has been promoted. For the heat release process in such the heat pump systems, the authors have studied on cooling heat transfer at supercritical pressures and condensation heat transfer at high subcritical pressures of refrigerants flowing in chevron-type plate heat exchangers (PHEs). In this study, to examine the effect of chevron angle on condensation heat transfer of refrigerants at high subcritical pressures, experiments were conducted using chevron PHEs with respective chevron angles 30°, 47.5° and 65°. In the experiments, condensation heat transfer coefficients were obtained in wide range of bulk fluid enthalpy comprising whole the saturated region, at pressures of reduced pressures from 0.65 to 0.80, and mass flow rates of 7 and 11 kg/min. The measured condensation heat transfer coefficient increased with the chevron angle. The increase rate of the condensation heat transfer coefficient against the chevron angle was compared with that of condensation heat transfer coefficient from a conventional correlation developed based on low subcritical pressures data and that of cooling heat transfer coefficient at a supercritical pressure from a previous experiment.

To achieve a good heat transfer performance for heat pump type air conditioners, the outdoor units of the air conditioners need to perform well under both the frosting and the non-frosting conditions. This paper proposes a perforated fin whose perforated structure is capable to enhance the heat transfer and to avoid the frost blockage. The perforate position on the fin surface is figured out by analyzing the positions of the frost blockage zone and the water exclusion zone. The optimal perforated geometries are designed to enhance the heat transfer coefficient. The new designed perforated fin has two parallels of rectangle multi-perforated holes. The experimental results show that the heat transfer capacities under the non-frosting condition and the frosting condition of the designed perforated fin are 4.6% and 1.1% higher than these of wavy fins, respectively. The perforated structure has the capability to avoid the frost blockage around the enhanced structure on the fin surface.

The active magnetic bearing (AMB) has many advantages compared with the conventional bearing. It is the most widely used bearing in many machine applications; such as centrifugal compressor, air blower, and turbo molecular pump. AMB applications must be equipped with auxiliary bearings system to prevent the damage to the impellers and motor in case of system failure. The auxiliary bearing is referred to as the touchdown bearing in this study. When a failure is occurred, the active magnetic bearing cannot support the rotor stably. Touchdown bearings serve as a backup for the active magnetic bearings to support the rotor during a drop-down failure event. Therefore, a properly designed touchdown bearing system is necessary to protect the active magnetic bearing assembly and other critical machine components from direct contact with the rotor during AMB loss in power outage events. This system uses a ball bearing as a type of touchdown bearing. A finite element based 2-DOF (two-degree of freedom) flexible rotor model is used to indicate the rotor behavior. The rotor model also considers the contact force between the shaft-inner race and ball bearing force based on Un-lubricated Hertzian contact models. This study presents a dynamic rotor simulation during a drop event applied in a magnetic centrifugal compressor. This simulation is built using MATLAB with rotor speed effect and touchdown bearing design to predict the rotor behavior based on the rotor orbit and response.

By a differential capillary rise method, the surface tension was measured for a new candidate of low GWP refrigerant HFO-1123. 16 points of surface tension data with a propagated uncertainty of approximately ±0.22 mN m^-1 are presented in this paper. Based on the measured data, a Van der Waals type empirical correlation was proposed for HFO-1123:  = 61.02 (1-T/Tcrit)^1.30 [mN m^-1], where Tcrit is a critical temperature of 331.7 K measured by Higashi and Akasaka. This empirical correlation agrees with the measured surface tension data at temperatures from 267 K to 304 K.

The driving range of electric vehicle can be significantly reduced if using CO2 as a refrigerant in hot climates. This paper aims to improve the performance of CO2 electric vehicle air conditioning system by using a dedicated propane mechanical subcooling, the interference between internal heat exchanger (IHX) and mechanical subcooling (MS) was discussed, since both improvements compete towards reducing the throttling losses, optimization possibilities were theoretically analyzed on several integrated system for various subcooling degrees from 3℃ to 15℃ and ambient temperatures from 25℃ to 40℃, results show that the presence of mechanical subcooling after IHX reduces its efficiency, the use of mechanical subcooling simultaneously before IHX rather yields a more efficient air conditioning system. It has been shown that compared with CO2 prototype system, the new best integrated system can improve the COP (coefficient of performance) up to a maximum of 25.72% despite the extra compression work in mechanical subcooling cycle, and the cooling capacity up to a maximum of 46.24% during the research range, thus, the driving range of EVs can be significantly extended. Furthermore, the suitable cooling capacity and propane compressor displacement required in the MS cycle are predicted. Finally, experiments were carried out to see the actual improvements achieved by MS and IHX cycle based on the theoretical results.

Experimental studies on the pVTx properties of the aqueous solution of ammonia were precisely conducted mainly in the liquid region. Based on these experimental results, it was experimentally confirmed that the existing range of the maximum densities was clarified in the dilute region of ammonia. Furthermore, in the vapor-liquid equilibrium states of the aqueous solution of ammonia, there exist large differences between the saturated vapor pressures, namely dew point line, and the saturated liquid pressures, namely bubble point line, and their discrepancies were thereof discussed including the influence of hydrogen bonding as same as in solid.

R32 is a refrigerant that excels in various applications and has seen wide use in recent years. However, R32 is known to have lower miscibility with refrigeration oils than do other refrigerants such as HFCs and HFOs. Moreover, when R32 is dissolved in refrigeration oils, the kinematic viscosity of the oil drops sharply. This has made it difficult to develop oils with improved miscibility with R32 that do not suffer from these drops in kinematic viscosity. Our work has shown that the addition of a new base material to POE improves miscibility with R32 while reducing the drop in kinematic viscosity that occurs when R32 is dissolved in it. Using this technology, we have developed new refrigeration oils whose critical solution temperatures were −20°C or below under R32 atmosphere. The kinematic viscosities of the new oils when R32 is dissolved in them were equal to or greater than those of POE oils currently used for R410A. In addition, the new oils have not only expanded the range of choices for POEs for R32, but also shown the possibilities for use with HFOs. In this study, we report our test methods and various characteristics of the oils under R32 and HFOs.