MODELING THE EFFECT OF HEAT EXCHANGE ON THE EFFICIENCY OF A THERMOELECTRIC COOLER

Author(s):  
O.I. MARKOV

Numerical modelling thermal and thermoelectric processes in a branch of solid–state thermoelectric of Peltier cooler is performed, taking into account heat exchange by convection and radiation. The numerical calculation of the branch was carried out in the mode of the maximum temperature difference.

2021 ◽  
Vol 315 ◽  
pp. 3-9
Author(s):  
Yuan Gao ◽  
Li Hua Zhan ◽  
Hai Long Liao ◽  
Xue Ying Chen ◽  
Ming Hui Huang

The uniformity of temperature field distribution in creep aging process is very important to the forming accuracy of components. In this paper, the temperature field distribution of 2219 aluminum alloy tank cover during aging forming is simulated by using the finite element software FLUENT, and a two-stage heating process is proposed to reduce the temperature field distribution heterogeneity. The results show that the temperature difference of the tank cover is large in the single-stage heating process, and the maximum temperature difference is above 27°C,which seriously affects the forming accuracy of the tank cover. With two-stage heating process, the temperature difference in the first stage has almost no direct impact on the forming accuracy of the top cover. In the second stage, the temperature difference of the tank cover is controlled within 10°C, compared with the single-stage heating, the maximum temperature difference is reduced by more than 17°C. The two-stage heating effectively reduces the heterogeneity of the temperature field of the top cover. The research provides technical support for the precise thermal mechanical coupling of large-scale creep aging forming components.


Author(s):  
Kwang-Chu Kim ◽  
Man-Heung Park ◽  
Hag-Ki Youm ◽  
Sun-Ki Lee ◽  
Tae-Ryong Kim ◽  
...  

A numerical study is performed to estimate on an unsteady thermal stratification phenomenon in the Shutdown Cooling System (SCS) piping branched off the Reactor Coolant System (RCS) piping of Nuclear Power Plant. In the results, turbulent penetration reaches to the 1st isolation valve. At 500sec, the maximum temperature difference between top and bottom inner wall in piping is observed at the starting point of horizontal piping passing elbow. The temperature of coolant in the rear side of the 1st isolation valve disk is very slowly increased and the inflection point in temperature difference curve for time is observed at 2700sec. At the beginning of turbulent penetration from RCS piping, the fast inflow generates the higher temperature for the inner wall than the outer wall in the SCS piping. In the case the hot-leg injection piping and the drain piping are connected to the SCS piping, the effect of thermal stratification in the SCS piping is decreased due to an increase of heat loss compared with no connection case. The hot-leg injection piping affected by turbulent penetration from the SCS piping has a severe temperature difference that exceeds criterion temperature stated in reference. But the drain piping located in the rear compared with the hot-leg injection piping shows a tiny temperature difference. In a viewpoint of designer, for the purpose of decreasing the thermal stratification effect, it is necessary to increase the length of vertical piping in the SCS piping, and to move the position of the hot-leg injection piping backward.


2011 ◽  
Vol 197-198 ◽  
pp. 1389-1394
Author(s):  
Sun Yi Chen

When the operating process of delay coking is cyclically changing from 25°C to 500°C, it would usually induce the effect of heat treatment on the shell of coke drum. After a special model of the kinetic medium climbing along the inside-wall of the coke drum at a steady rate set up, the resulting two-dimensional kinetic temperature field of shell in radial and axial directions has been calculated and analyzed by FEM. The relation between the material physical property of the shell and its temperature has been considered. The results show that the radial temperature difference or the axial temperature difference caused by the cooling water is more than that caused by the hot oil. The maximum temperature difference between the inside-wall and the outside-wall is 40°C below the medium level, 30mm by the hot oil and 60 °C or 25 mm by the cooling water. The circumferential uneven temperature field, location and concave/convex or incline/bend of body have been surveyed and analyzed. The lat-circle deformation of transverse section has been discussed.


2017 ◽  
Vol 5 (3) ◽  
pp. 404-413
Author(s):  
Sravankumar Jogunuri ◽  
Navneet kumar ◽  
Farid Gayasoddin Sayyad ◽  
Valand Pinakin ◽  
Vishal Patel

A Multi-Purpose Solar Food Processor (MCSFP) was developed to carryout both cooking and drying operations simultaneously. MCSFP was tested in three different modes of operations ie., for fenugreek leaves drying (M1) and for cooking of rice separately (M2) and drying of fenugreek and cooking of rice together(M3). The maximum temperature difference attained between ambient air and MCSFP dryer and cooker was 23°C and 36.5°C respectively. The temperatures attained are well suited for drying of fenugreek leaves and cooking rice.


Climate ◽  
2020 ◽  
Vol 8 (6) ◽  
pp. 69 ◽  
Author(s):  
Kai Gao ◽  
Mattheos Santamouris ◽  
Jie Feng

Trees are considered to be effective for the mitigation of urban overheating, and the cooling capacity of trees mainly comes from two mechanisms: transpiration and shading. This study explores the transpiration cooling of large trees in urban environments where the sea breeze dominates the climate. In the experiment, sap flow sensors were used to measure the transpiration rate of two large trees located in Sydney over one year. Also, the temperature difference between the inside and outside of the canopy, as well as the vertical temperature distribution below the canopy, were measured during summer. In this experiment, the temperature under the canopies decreased by about 0.5 degrees from a 0.5 m height to a 3.5 m height, and the maximum temperature difference between the inside and outside of the canopy was about 2 degrees. After applying a principal component analysis of multiple variables, we found that when a strong sea breeze is the primary cooling mechanism, the sap flow still makes a considerable contribution to cooling. Further, the sea breeze and the transpiration cooling of trees are complementary. In conclusion, the characteristics of synoptic conditions must be fully considered when planting trees for mitigation purposes. Since the patterns of sea breeze and sap often do not coincide, the transpiration cooling of trees is still effective when the area is dominated by sea breeze.


Author(s):  
Yoshio Fukushima ◽  
Masataka Kosaka

Abstract Much focus from various fields is being placed on the hydrogen and utilizing the technique. Nowadays, the applied researches of hydrogen energy have been trying as one of an alternative energy source for fossil fuel. And, since we could not think lightly of consumed energy by machine tools and industrial machinery, Eco-friendly manufacturing is going to be achieved by hydrogen energy. In this study, to prevent the weldline that is a representative defect in the field of plastic injection molding, heat & cool technology using hydrogen energy, LmNi4.90Mn0.10 hydride, is applied to the mold. This method can achieve heat & cool technology by using only hydrogen energy. So, since electricity and warm/cool water that are for heating/cooling the mold are not necessary, this method should thus be at an engineering advantage in terms of eco-friendly manufacturing. After manufacturing the hydrogen-used-prototype-mold that is dedicated to preventing the weldline, the comparison between the experimental data and numerical simulation was carried out. As result, using this approach, the mold surface temperature difference from initial temperature was rapidly increasing to 40 K, in 18 seconds from the beginning of hydrogen-absorbing and the maximum temperature difference ΔT in this experiment has become 48 K.


2018 ◽  
Vol 53 ◽  
pp. 03045
Author(s):  
Jiao Yuan ◽  
Jingwen Li ◽  
Suxian Ye ◽  
Xiaoqiang Han ◽  
Yao Hu

Using a spatial resolution of MODIS land 1000m standard products, we can get the Land Surface Temperature.Researching for the Land Surface Temperature including spatial and temporal distribution characteristics influence factors.The results show that Spring,Summer and Autumn temperatures mainly concentrated in the central region,Winter temperature mainly concentrated in the South region.From 2001 to 2015,the maximum temperature difference is summer daytime and the difference is 17.58°C,the minimum temperature difference is autumn daytime and the difference is 11.3°C.According to the thermal field intensity distribution,compared 2005 with 2015,Urban Heat Island intensity gradually increased in 2015,the high temperature area increased and distributed more concentrated,and diffusion weakened from the city to the surrounding,the urban heat field is higher than the thermal field.That index by calculating the thermal landscape,account for a dominant position in the middle of heat distribution,and all types index in 2015 are higher than in 2005.


2014 ◽  
Vol 563 ◽  
pp. 133-136
Author(s):  
Chun Lai Tian ◽  
Shan Zhou ◽  
Li Yong Han

A numerical simulation model of heat flux sensors embedded in a flat plate is established. Each sensor has four thermal couples and is inserted into the specified hole. The problem is defined as a steady heat conduction problem with specified boundary conditions and solved by the finite element method. The results of the simulation case demonstrate that the maximum heat flux appears near the sensor shell. The average heat flux of the plate is much smaller than the maximum. Due to exiting of the contact heat resistance, the temperature of the sensor is much lower than that of the plate at horizontal surface. The maximum temperature difference appears on the bottom shell of the sensor. The maximum temperature difference between the simulation results and the experimental data at test points is 1.5 K. The model is verified and could be accepted for the further errors analysis.


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