• Food Science and Preservation
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• v.23 no.4
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• pp.471-478
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• 2016

For the distribution of fresh produce, the thermoelectric cooling system combined with thermo electric materials (TEM) and phase change material (PCM) was studied. The PCM used this study was produced by in-situ polymerization technology which referred microencapsulation of hydrocarbon (n-tetradecane and n-hexadecane). In this study, quality characteristics of bell peppers in thermoelectric cooling system combined with TEM and PCM were analyzed and control was placed in an EPS (expanded polystyrene) box. As a result of quality characteristics analysis, weight of bell peppers decreased and moisture content of bell peppers was 90.96~94.43% during storage. Vitamin C content of bell pepper decreased during storage and reduction ratio of control was higher than that of BPT-5 treatment(bell pepper in thermoelectric cooling system with PCM which is kept the temperature at $5^{\circ}C$). The result of color value, on 21 day, ${\Delta}E$ value of BPT-5 treatment was 5.05 while that of control was 41.8. On 21 day, total bacteria count of BPT-5 treated bell pepper shown less than that of control. In conclusion, it suggested that the thermoelectric cooling system combined with PCM improved quality of fresh produce during transportation and storage.

• Food Science and Preservation
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• v.15 no.1
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• pp.15-20
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• 2008

By considering the storage temperatures of agricultural products, three types of PCMs $(K_1$, $K_2$, $K_3$) were developed to be used in temperature ranges of $0{\sim}5^{\circ}C$, $5{\sim}10^{\circ}C$ and $10{\sim}15^{\circ}C$, $K_1$ PCM for $0{\sim}5^{\circ}C$ was developed by mixture of $C_{14}H_{30}$ and soduim polyacrylate, and $K_2$ PCM for $5{\sim}10^{\circ}C$ and $K_3$ PCM for $10{\sim}15^{\circ}C$ were mixture of $C_{14}H_{30}$, $C_{18}H_{38}$ and soduim polyacrylate with different composition ratio. 'The target temperatures of cold chain system were set at $7^{\circ}C$, $13^{\circ}C$, and $17^{\circ}C$ with $K_{1-3}$, $K_{2-3}$ and $K_{3-1}$ PCMs, respectively. The times to reach the target temperatures in the storage chamber were 21 hours, 18 hours, and 61 hours with $K_1$, $K_2$, and $K_3$ PCMs, respectively. The performances of natural convection type and forced convection of the temperature controlled portable container were analyzed Apples were stored in the portable container of $5^{\circ}C$, and temperatures at surface and center were measured. The initial temperature of the apple was $25^{\circ}C$. The temperatures of apple at the surface and the center were $15^{\circ}C$ and $16^{\circ}C$, respectively, after 5 hours with natural convection type. However, the temperatures at the surface and the center were already reached to $7^{\circ}C$ within 1 hour with forced convection type. The forced convection type showed the better performance and the temperatures of portable container were maintained more than 15 hours.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.2
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• pp.173-178
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• 2010

The ice storage system uses water for low temperature latent heat storage. However, a refrigerator capacity are increased and COP are decreased due to supercooling of water in the course of phase change from liquid to solid. This study investigates the cooling characteristics of the TMA-water clathrate compound including TMA (Tri-methyl-amine, $(CH_3)_3N$) of 20~25 wt% as a low temperature latent heat storage material. The results showed that the phase change temperature are increased and the supercooling degree and the specific heat are decreased according to the weight concentration of TMA increased. Especially, the clathrate compound containing TMA 25wt% has the average phase change temperature of $5.8^{\circ}C$ and the supercooling degree of $8.0^{\circ}C$, retention time of liquid phase for 651sec and specific heat of 3.499 kJ/kgK in the cooling process. This expressed good than different concentration of TMA cooling characteristic. Like this, to apply TMA 25wt%-water clathrate compound is determined by advantageous as the low temperature latent heat storage material.

• Transactions of the Korean Society of Automotive Engineers
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• v.15 no.1
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• pp.23-28
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• 2007

This study aims to find out cooling characteristics of TMA(Tri-Methyl-Amine, $(CH_3)_3N$) 25wt%-water clathrate compound with ethanol($CH_3CH_2OH$) such as supercooling, phase change temperature and specific heat. For this purpose, ethanol is added as per weight concentration and cooling experiment is performed at $-6{\sim}-8^{\circ}C$, cooling heat source temperature, and it leads the following result. (1) Phase change temperature is decreased due to freezing point depression phenomenon. Especially, it is minimized as $3.8^{\circ}C$ according to cooling source temperature in case that 0.5wt% of ethanol is added. (2) If 0.5wt% of ethanol is added, average supercooling degree is $0.9^{\circ}C$ and minimum supercooling is 0.8, $0.7^{\circ}C$ according to cooling heat source temperature. The restraint effect of supercooling is shown. (3) Specific heat shows tendency to decrease if ethanol is added. It is $3.013{\sim}3.048\;kcal/kg^{\circ}C$ according to cooling heat source temperature if 0.5wt% of ethanol is added. Phase change temperature higher than that of water and inhibitory effect against supercooling can be confirmed through experimental study on cooling characteristics of TMA 25wt%-water clathrate compound by adding additive, ethanol. This can lead to shorten refrigerator operation time of low temperature latent heat storage system and improve COP of refrigerator and efficiency of overall system. Therefore energy can be saved and efficiency can be improved much more.