For the gas-liquid two-phase refrigerant flow in the multi-pass channel with a vertical header and horizontal branch tubes that simulates the parallel-flow type heat exchanger used for residential and commercial air conditioners, the influence of evaporation of liquid refrigerant in branch tubes on the gas-liquid distribution characteristics in the channel was experimentally investigated. The test channel had a vertical header with a height of 81.5 mm and 8 horizontal aluminum microchannel branch tubes connected in parallel to the header at a pitch of 10 mm, and all the branch tubes were heated evenly at 20 – 100 W/tube. It was found that the excessive liquid distribution to the lowermost branch tube was suppressed by heating the branch tubes, while the amount of liquid distributed to the upper branch tubes increased. As a result, the uniformity of the liquid distribution was improved by the evaporation of the liquid refrigerant in branch tubes.

Anomaly prediction and diagnosis of various machinery using IoT technology have been widely studied． Although air conditioners are commonly used in many facilities， few studies have focused on anomaly diagnosis， especially for small and medium-sized air conditioners．In this study， we propose an approach for installing a data collection and diagnosis system for existing air conditioners． Some of the challenges faced in detecting and diagnosing anomalies in air conditioners include noisy environments， cost constraints， and seasonal changes of targets． Therefore， careful coordination of the data collection system and the diagnosis method， and constructing a diagnostic model for each season, and utilizing pressure data estimates in addition to vibration data could realize an effective and inexpensive anomaly detection system for air conditioners．

We investigated the flow pattern of ice slurry flowing in a horizontal pipe, changing the flow velocity and IPF as parameters. In this study, we proposed original flow patterns suitable for ice slurry flow. Effects of bubbles and agglomeration of ice particles were considered as a major factor. As a result, the flow pattern of ice slurry can be divided to 3 patterns. When the flow velocity and IPF are high, it forms homogeneous flow, in which ice particles are homogeneously dispersed. It was found that ice slurry containing bubbles is easy to form homogeneous flow. We suppose that this is the effect of the repulsive force between the bubbles adhering the ice particles in the ice slurry. It forms cluster flow, when the ethanol concentration of the solution in the ice slurry is low, because agglomeration force of ice particles increases. It was also found that ice slurry containing bubbles is easy to form homogeneous flow, comparing with it without bubbles, even when the ethanol concentration of the solution is the same, under the same condition (flow velocity and IPF). We suppose that the agglomeration forms due to the contacts of ice particles. However, the contacts are inhibited when the bubbles are contained in the ice slurry, because of the repulsive force of the bubbles, and the agglomeration of the particles are also inhibited.

In previous study, the refractive index of water was measured under microwave irradiation and the stability of the hydrogen bond network was discussed from the reduction level. In order to clarify the stability for hydration of electrolyte solution, refractive index of the sodium chloride aqueous solution was measured during various modes of microwave irradiation. Hydrogen bond network structure of water or sodium chloride solution of lower concentration is easily broken by microwave irradiation of higher power. However, because the network was stronger at the higher concentration, the collapse became more difficult even by the higher power. Additionally, data during the pulse irradiation with different intervals showed recovery of hydrogen bond network collapsed by the irradiation, and non-thermal microwave effect for aqueous solution of higher concentration does not last for a long time.

Agglomeration of ice particles in ice slurry flow was investigated. The flow pattern of ice slurry was classified into 2 patterns. One is the blocking flow, in which agglomeration of ice particles occurs in the slurry. The other is the non-blocking flow, in which agglomeration does not occur. First, observations of flow pattern of ice slurry in the vertical and horizontal tubes were performed, to investigate of the effect of gravity. Since the difference in flow pattern between vertical and horizontal flows is not significant, it was found that the effect of gravity is relatively small. Second, the observations in horizontal tube were performed under different initial IPF conditions, to investigate the effect of the diameter of ice particles in the slurry. From the observation, it was found that the ice particles cause agglomeration at the initial condition, and they gradually become small spherical shape and well-dispersed due to the melting of the ice. As a result, non-blocking flow appears under higher IPF conditions, when the initial IPF is higher and ice particles are smaller. We presumed that the agglomeration is inhibited when the particle size is small, because the adhesion area decreases, or the effect of fluid force becomes relatively larger.

In this study, experimental investigations were conducted on the magnitude of expansion pressure generated by the solidification of pure water and aqueous solution, as well as on the effect of aqueous solution concentration on the mechanism of expansion pressure generation. In particular, the effect of the concentration gradient in the container which has the large aspect ratio for the vertical direction. In particular, by focusing on a thermal storage vessel with a large aspect ratio in the longitudinal direction, the effect of the concentration gradient in the vessel on the growth of the solidified layer was observed using an optical visualization technique. As a result of this study, it was clarified that the expansion pressure generated during solidification becomes smaller as the concentration of the test solution increases, on the other hand, this pressure is not affected by the magnitude of the concentration gradient of the solution in the height direction inside the vessel.

In this study, the flow characteristics of the xylitol slurry, which is expected to be used as a heat storage and heat transport medium, in a horizontal circular tube were experimentally investigated. The experimental results showed that the flow of xylitol slurry can be classified into heterogeneous flow with sedimentation of xylitol particles and homogeneous flow with homogeneous dispersion of xylitol particles, depending on the ratio of the mean flow velocity to the terminal velocity of xylitol particles. Rheological properties of the xylitol slurry were investigated, and it was found that the xylitol slurry exhibits Newtonian-fluid behavior in the range of 5–15 wt% of solid fraction. It was also found that the apparent viscosity of xylitol slurry can reasonably be estimated by Einstein’s equation, Thomas’ equation and Mooney’s equation.

We focus on fatty acids (capric acid, lauric acid and myristic acid) and their mixture having unique phase change characteristics as a working fluid for a heat exchange system with multistage latent heat storage. These fatty acids as heat storage materials are easy to handle and less influenced on human body near ambient conditions. When the fatty acids mixed with a suitable mixing ratio are in the liquid phase state, the thermophysical properties (thermal conductivity and specific heat) were identified in order to establish a new heat exchange system with multistage latent heat storage. As a result, thermophysical properties such as specific heat and thermal conductivity of the fatty acids and their mixture were evaluated quantitatively and were newly proposed as an appropriate heat transfer database. The database was also evaluated quantitatively with an appropriate uncertainty analysis method.