This paper presents a review on flow behavior and heat transfer of ice slurry, focusing on the works especially in the recent decade. Ice slurry was firstly picked up at 1990s, and many fundamental studies were performed in the early years. Based on them, it develops to advanced stage recently. Physical phenomenon of flow and heat transfer characteristics of ice slurry attracts a lot of researchers. On the other hand, investigations for practical applications, for example using ice slurry in commercial heat exchangers, were also performed. The knowledge related to such physical phenomenon and applications are summarized in this paper. Moreover, future prospect of the study in this field and the considerations required to use ice slurry in the future applications, such as cooling/refrigeration of foods, medical use, was described.

Ice adhesion to a cooling solid surface, especially, a cooling metal surface, often occurred in various situations. And these ice adhesions sometimes result in a serious accident. Thus, it is essential to clarify phenomenon of ice adhesion, especially, ice adhesion force to a metal surface. The ice adhesion force to the metal surface has been usually measured by acting a shearing force at the interface between the metal surface and ice in a macro-scale, but the measured ice adhesion force is an apparent value including a force to break the ice due to unevenness of the metal surface. In order to measure accurate ice adhesion force without breaking, one of the authors developed the measurement method in a nano-scale using scanning probe microscope (SPM). In this study, the ice adhesion force without breaking on copper surface was measured, varying the surface temperatures, after which validity of the temperature-dependency on the ice shearing stress defined as ice adhesion force per ice adhesion area was investigated by comparing with that on the surface energy of the copper at various temperatures cited in the references and conventional macro-scale results.

In the present study, the heat transfer characteristics of a phase change emulsion (PCE) were investigated experimentally to use it as one of the high functional thermal media. The wall heat flux, mass fraction of phase change materials and particle phases were chosen as factors which effect on the heat transfer characteristics of PCE. The particle phases were divided into three cases that solid phase, liquid phase and melting. Two kinds of phase change materials (PCM), n-hexadecane and n octadecane were used as the dispersed phase of PCE. The experiments were carried out in a laminar flow region. The results showed the local Nusselt number of PCE in cases of PCM particles were in solid or liquid phases roughly agreed to the empirical values which were calculated by an empirical equation for the single phase flow. On the other hand, when PCM particles were melting, the local Nusselt number of PCE became 1.3 – 1.8 times higher than the empirical value. Furthermore, the results of PCE with 20 mass% PCM roughly agreed to numerical values obtained by solving the energy equation for a steady two dimensional developed flow in a circular duct applying FDM.

Tetra-n-butyl ammonium bromide (TBAB) hydrate has been attracting attention as a thermal storage material, since the phase change temperature of TBAB hydrate is from 5 to 12 °C and it is optimal for a thermal storage material of the air-conditioning. However, the TBAB solution tends to be supercooled. In this study, the effect of an DC voltage application on hydrate nucleation in supercooled TBAB aqueous solution was investigated experimentally. The electrode was inserted into the TBAB solution under room temperature, and DC voltage applied to the TBAB solution. After that, the electrode was extracted from the solution and the sample was cooled under a supercooled state. The electrode material, the concentration of TBAB aqueous solution and the duration for the DC voltage application were varied as the experimental parameters. It was found that the probability of nucleation becomes higher due to the DC voltage application, and the probability depends on the amount of the electric charge during the DC voltage application. Moreover, it was found that the probability of nucleation depends on the electrode material. The probability of nucleation is especially high in the case of the Cu, Ag and Zn electrodes.

Absorption ice slurry generator is proposed for low-level unused energy utilization. Ice slurry is generated by absorption refrigeration cycle using ethanol solution as a refrigerant, and LiBr-water-ethanol mixture as an absorbent. In advance, the saturated pressure of the mixture of 3 components was measured, since it has not been known. Using the measured data, the COP of the ideal cycle of this absorption ice slurry generator was estimated. As a result, we concluded that this system will be useful, because the COP of this cycle is comparable with existing absorption refrigerators. Using double lift cycle, the temperature of evaporator/ice slurry can be decreased below −15°C. Due to this, the use application of the ice slurry will be expanded. Additionally, this cycle is suitable for low-level unused energy utilization, because it can be operated by relatively

In this study, an experimental investigation was carried out to study the heat transfer between a vertical impingement ice slurry jet and a horizontal rectangular heated surface. In this experiment, the influence of the latent heat of fusion of the ice slurry is investigated. A salt-water solution, ice slurry, and water absorption polymer slurry are used as the test fluids. The jet flow rate, heated surface temperature, and ice packing factor (IPF) of the ice slurry are used as experimental parameters. The experimental results show that the heat transfer coefficient of the ice slurry is the highest among three types of liquids. This indicates that using ice slurry as a heat transfer medium can enhance the heat transfer process. The results also show that the heat transfer characteristics is strongly affected by the physical properties of the jet flow, the impinging jet flow rate, IPF of the ice slurry, and the heat flux of the heated surface.

We carried out an experiment to measure ice crystal orientation growing through a resin rectangular tube. It was found that c-axis of the ice crystal becomes likely to be nearly perpendicular to a wider wall of the rectangular tube. Probabilities of success of c-axis of ice within 15 degrees of perpendicular was showed at each temperature. The results exhibited that the rectangular tube can keep higher the probability of success than a stainless capillary bended into triangular-waves, especially at lower temperature. Then, using the twisted tube twisting 90 degrees, we carried out the same experiments. In the result, it was confirmed that a probability of success of the twisted tube is very low at higher temperature, but the probability reaches over 95% at minus 3 degrees Celsius. Finally, from these results, we discussed about phenomenon of change of ice crystal orientation during growth, and predicted that high probability of success will be achieved over a wide range of temperature by using a rectangular tube made of a suitable material and twisted with a suitable pitch.

Recently high efficiency heat transport medium is required for high temperature applications, more than 100 C, such as utilization of solar heat or unused industrial wasted heat. In this research, erythritol slurry, which is the mixture of erythrtil solution and its fine crystals, is proposed as a candidate for the heat transfer medium and heat storage material. In the experiment, pipe friction coefficient and apparent specific heat of erythritol slurry were measured. It was found that erythritol slurry has a good fluidity in adequate solid fraction range, and it has significantly higher heat storage capacity comparing to water or erythritol solution. As a result, we concluded that erythritol slurry is capable as a new heat transport medium.

This study experimentally investigated the heat transfer and pressure drop characteristics for evaporation and condensation flows of the refrigerant mixture, R245fa/R134a, which is used as a working refrigerant for a high-temperature heat pump and binary generator of an organic Rankine cycle inside horizontal tubes. The evaporation and condensation flow₂ s were measured at an average saturation temperature of 40 and 60 °C, respectively, at mass velocities of 100 to 200 kg/m s, and using the following four composition refrigerant mixtures of R245fa/R134a: 90/10, 80/20, 65/35, and 55/45, mass ratios of R245fa to R134a. The evaporation and condensation heat transfer coefficients and frictional pressure drops of the refrigerant mixtures were lower than those of the pure refrigerant, R245fa. Further, the evaporation and condensation heat transfer coefficients and frictional pressure drop decreased with an increasing mass ratio of R134a. The frictional pressure drops for the evaporation and condensation flows of the refrigerant mixtures were consistent with the previous correlation; their correlation accurately predicted frictional pressure drops of pure refrigerant. The heat transfer coefficients of the refrigerant mixtures in the microfin tube contained a lower heat transfer enhancement from the spiral fins than that of the pure refrigerant. In addition, the heat transfer enhancement for the condensation flow was higher than that for the evaporation flow. Even when the refrigerant composition and mass velocity were varied, the heat transfer coefficient of the refrigerant mixtures in the microfin tube was higher than that in the smooth tube.

This study suggests using the double effect adsorption cycle to utilize adsorption heat with a compressor with a view to improving the cycle performance below 80degC. The aim of this study is to comprehend the effect of the compressor on the cycle performance. The effect of the desorption pressure on the cycle performance was examined with the help of static analysis assuming equilibrium states. The adsorption cycle can work under a lot of changes due to adjusting the desorption pressure regardless of the external temperature like the heat source and cooling water. As a result, the hybrid double effect adsorption refrigeration cycle is the efficient refrigeration cycle and can enhance the performance. COP, SCE and exergy efficiency were improved by adjusting the desorption pressure and COP amounts to 1.2 from 60 to 80degC.

Nowadays, fluorescence spectroscopy has been used as a potential method for nondestructive quality measurement of food materials. Fluorescence fingerprint (FF) of adenosine 5’-triphosphate (ATP) has been observed during the quality assessment of different raw food materials. Although the fluorescence spectra of ATP can be affected by various factors including pH, the details are not clarified yet. Thus, the study attempts to demonstrate the effects of pH (5.0-8.0) on the FF data of ATP standard solutions (10, 5 and 1 µmol/mL for both frozen and non-frozen states). The results of the present study revealed that the strength of the fluorescence signal was influenced by not only the concentration of ATP but also by the pH of samples. The highest fluorescence intensities were observed from the non-frozen ATP solutions at pH 5.0 for each concentration which declined drastically with increasing pH. The majority of frozen ATP samples showed the similar trends of wavelength conditions to get highest fluorescence intensity. Small pH changes affected the intensity and spectral characteristics of FF and it even shifted the peak wavelength conditions. The implementation of this method would be a help to ensure the validity of FF and optimize it as a technique that can be used to verify the effects of pH on many constituents of food.