Development of cold‐hot water dispenser with thermoelectric module systems

In the present study, the results of a cold‐hot water dispenser with a thermoelectric module system (TMS) are presented. The cold‐hot water dispenser with thermoelectric module system consists of a cold water loop, a hot water loop, a coolant loop, and a thermoelectric module. The thermoelectric cooling and heating modules consist of four and two water blocks, nine and three thermoelectric plates, respectively. The cooling and heating capacities obtained from the cold‐hot water dispenser with TMS are compared with those from a conventional cold‐hot water dispenser with a compression refrigeration system (CRS). As compared with the conventional cold‐hot water dispenser with CRS, the cold‐hot water dispenser with TMS can be operated at the minimum cold water temperature of 10 to 13°C and the maximum hot water temperature of 65°C. The obtained results are expected provide guidelines to design cold‐hot water dispensers with TMS.     

Experimental Study of the Effect of the Helical Ribs in a Spirally Coiled Tube on the Friction Reactor and the Nusselt Number of a Nanofluid Flow in it

Journal of Engineering Physics and Thermophysics - The effect of the centrifugal force arising in a spirally coiled tube with helical ribs on the heat transfer in the fluid flow in it was...     

Waste heat recovery from household biomass gasifier stoves (HBGSs) for thermoelectric generators: Effect of the primary air valve angle

Household biomass gasifier stoves (HBGSs) are used in remote areas using natural firewood that is burned in the HBGS for general purposes, such as cooking and warming in winter. The heat dissipation from the walls is assumed to be heat loss. This paper evaluates the electrical performance of thermoelectric generators (TEGs) using heat recovered from the hot walls of an HBGS, considering the effect of three primary air valve angles of 0°, 9°, and 18°. The heat recovered from the HBGS that is electrically transferred through a TEG is assessed. The results showed that the wall heat loss increases with the primary air valve angle of the HBGS. The upper zone near the HBGS gas combustion zone exhibits higher wall temperatures than the middle and lower zones, with a maximum wall temperature of 140°C resulting in an output voltage of 2.55 V. However, the middle and lower zones are also considered as their capacities are consistent with the TEG temperature range. The heat loss from the HBGS is considerably larger than that from other heat sources, and the specific heating area of the heat source is a variable that should be considered to increase the number of TEGs to achieve the desired output values for practical applications. Furthermore, this research serves as a guideline for applying TEGs to recover waste heat from various applications.     

Effect of heat source area on the thermal resistance of the wick columns vapor chambers

The results of the spreading thermal resistance, heat transfer and flow characteristics of the vapor chamber embedded with plate fin are investigated. The experiments are performed with the vapor chambers with wick plate and wick columns embedded plate fin. Parametric studies including different heat fluxes, heated surface areas, flow rate of coolants on the cooling performance in terms of the spreading thermal resistance and heat transfer characteristics are considered. A three-dimensional heat and mass transfer model for the vapor chamber with wick plate and wick columns are developed. The velocity and pressure distributions of liquid phase and vapor phase inside the vapor chamber obtained from the simulation are shown. By comparing the experimental results with numerical results, reasonable agreement is obtained. It can be found that the heat input and heat source area have significant effect on the decreasing of the boiling and condensation thermal resistances while they are slightly effect on the decreasing of the convective thermal resistance. Due to the wick plate and wick columns, the capillary force has significant effect on the working fluid circulation, evaporation rate and flow directions of the liquid and vapor phases inside the vapor chamber. The results of this study are of technological importance for the efficient design of cooling system of the personal computer or electronic devices to enhance cooling performance of the vapor chamber.

     

On the thermal cooling of central processing unit of the PCs with vapor chamber

An experimental investigation on the thermal cooling of vapor chamber for cooling computer processing unit of the personal computer is performed. Two different configurations of the vapor chambers with de-ionized water as working fluid are tested under the real operating conditions of PCs. Parametric studies including different aspect ratios, fill ratios, and operating conditions of PC on the CPU temperature are considered. It was found that the vapor chamber cooling technique has significant effect on the thermal cooling of CPU. Average CPU temperatures obtained from the vapor chamber cooling system are 4.1%, 6.89% lower than those from the conventional cooling system for no load and 90% operating loads, respectively. In additional, this cooling system requires 6.89%, 10.53% lower energy consumption for no load and 90% operating loads, respectively. The results of this study are of technological importance for the efficient design of cooling systems of the personal computers or electronic devices to enhance cooling performance.     

Study on the vapor chamber with refrigerant R-141b as working fluid for HDD cooling

The heat within the operating drive is mainly generated by the SPM, VCM, magnetic read/write head sensor, and windage loss. Temperature is often quoted as the most important environmental factor affecting disk drive reliability. The results of the investigation on the thermal cooling of vapor chamber with refrigerant R-141b as working fluid for cooling hard disk drive are presented. It was found that the vapor chamber cooling technique has a significant effect on the thermal cooling of hard disk drive. At the optimum condition (20% fill ratio of working fluid) that results in minimum HDD temperature, average HDD temperatures of VC with refrigerant R-141b as working fluid are 10.73% and 23.37% lower than those with water as working fluid and those without VC, respectively. The results of this study are of technological importance for the efficient design of cooling systems of the personal computers or electronic devices to enhance cooling performance.     

Liquid cooling in the mini-rectangular fin heat sink with and without thermoelectric for CPU

In the present study, the liquid cooling in the mini-rectangular fin heat sink with and without thermoelectric for CPU is studied. Six mini-rectangular fin heat sinks with two different material types and three different channel widths are fabricated from the copper or aluminum with the length, the width and the base thickness of 37, 37, 5 mm, respectively. The de-ionized water is used as coolant. Effects of channel width, coolant flow rate, material type of heat sink and run condition of PC on the CPU temperature are considered. The liquid cooling in mini-rectangular fin heat sink with thermoelectric is compared with the other cooling techniques. The thermoelectric has a significant effect on the CPU cooling of PC. However, energy consumption is also increased. The results of this study are expected to lead to guidelines that will allow the design of the cooling system with improved heat transfer performance of the electronic equipments.     

Heat transfer performance of thermoelectric cooling integrated with wavy channel heat sink with different magnetic distances

Thermoelectric cooling (TEC) reverses the electrical energy to temperature caused by the Peltier effect, where a temperature difference occurs between two conductors, that is, hot and cold junctions. This article presents the enhanced heat transfer of a TEC module using a TEC1-12710 model integrated with a wavy channel heat sink using ferrofluid as a coolant under continuous and pulsating flows, where the differences in the distance of the magnetic field are considered. Square permanent magnets measuring 30 mm × 20 mm × 4 mm (width × length × height) are used to transmit a magnetic field to the heat sink and then tested under a magnetic distance of 10–30 mm. The test is performed at a water flow rate from 0.0083 to 0.028 kg/s and supplied with a constant TEC voltage of 12 V. By applying a magnetic field to the TEC module with a magnetic distance of 20 mm and a ferrofluid concentration ratio of 0.015%, the cooling efficiency increases by approximately 18.64%. Hence, using pulsating flow may improve thermal efficiency by approximately 23%. The results show an exponential increase in the cooling efficiency when both passive and active cooling techniques are used.