جستجوی مقالات مرتبط با کلیدواژه « ترموسیفون » در نشریات گروه « مکانیک »

In conventional vehicles, about 40% of fuel energy is converted into useful power, and the rest is directed to the environment by cooling and exhaust systems, which, in addition to energy loss, are also one of the main sources of air pollution. At present, all over the world, food suppliers use online orders for their customers to move ready-made food from the place of production, such as restaurants, to their destination while maintaining its quality. However, along this route, due to the long distances that cause heat loss from the food container, it creates problems for food to cool or heat drinks in online orders. Therefore, using a thermosyphon in the exhaust gas path to recover waste heat is one of the methods that can be used in addition to solving the problem of existing pollution with heating applications and also for cooling applications of vehicle electricity as chamber cooling. In this research, a mobile combined cycle (heating-cooling chamber) was used to keep the chamber warm with the best filling percentage of 75% in all inlet capacities for 25 minutes to about 48 °C using a thermosyphon and cool the other chamber for 8 minutes. It was designed and built up to a temperature of about 5 °C with the help of thermoelectric cooling.

In a variety of industries, thermosyphons are used to improve heat transfer. High reliability, easy maintenance and repairs, high thermal conductivity, and isothermal heat transfer are among its benefits. Thermosiphon is used for a variety of things, including cooling electronic components and air conditioning. In the studies conducted on the thermal performance of thermosyphons, it has been determined that the type of working fluid is very important. For this purpose, in this research, the thermal behavior of thermosyphons using two different working fluids has been investigated experimentally. A copper tube with a length of 1000 mm, an external diameter of 22 mm, and an internal diameter of 20 mm is used to construct the thermosyphon previously mentioned. The thermosyphon was tested with two working fluids—methyl acetate and deionized water—and three filling ratios—55%, 70%, and 85%—along with thermal loads ranging from 50 to 300 W and at a distance of 50 W. The results of the experiments revealed that this thermosyphon had a lower thermal resistance in the filling ratio of 70% of both fluids. Additionally, methyl acetate outperformed deionized water in terms of thermal performance by about 20–50%

The design of air conditioning systems is one of the effective factors in optimizing energy consumption in residential and commercial buildings. In this study, the performance of a solar chimney with different solar thermal flux on it and the use of an absorbent wall in the chimney have been investigated. Increasing the air temperature adjacent to the absorbing wall has the effect of thermosyphon in the chimney that ultimately leads to continuous air movement inside the chimney. In most of the proposed designs for these chimneys, the absorbing wall is one of the sidewalls. With sunlight warming up the wall, the air flows into the chimney. By heating the absorbing wall and increasing the temperature gradient, some heat in this wall will be lost through the conduction phenomenon in the wall thickness to the outside or inside the building. In the proposed scheme, the absorbing wall is located in the middle of the chimney and since the optimum width for the chimney is between 0.2m and 0.3m, in the proposed scheme, the distance between each wall and the intermediate absorbing wall is equal to 0.25m. In order to simulate the flow field, the equations of mass, momentum, and energy conservation are solved in the two-dimensional form with constant, incompressible, and turbulent flow assumptions simultaneously. To solve the equations, an academic code based on Fortran's language and SIMPLE algorithm is used. Due to the nature of the turbulent flow of air within the solution field, the $k-varepsilon$ turbulent model is used because of the good performance of this model in simulating boundary layer flows with high reciprocating gradients. The intensity and concentration of heat transfer and geometric parameters related to the solar chimney, such as the entrance area, the thickness and length of the absorbing wall, and the location of the absorbing wall in the amount of discharged air flow have been investigated and the optimal values for maximum air discharge have been extracted. Moreover the absorbent wall partitioning is presented as a novel solution to increase the thermosyphon phenomenon in the solar chimney.

The heat pipe as superconductors can play an essential role in heat transfer According to the application, are designed in different sizes The heat pipe for heat transfer with very high thermal conductivity that heat energy by evaporation and condensation of a working fluid with minimal temperature drop pass When the heat of evaporation area is the working fluid evaporates and creates a pressure gradient in the tube The steam pressure gradient along the tube makes the move to steam condenser condenses in the condenser is, the latent heat is released. The working fluid of the heat pipe by gravity thermosyphon returns to the evaporation zone In this study the vapor and liquid inside the heat pipe is modeled thermosyphon type It is assumed that the flow is permanent and peaceful two-dimensional and volumetric forces have been ignored. In this paper, the finite volume method and SIMPLE algorithm is used. The geometry of the model with the software Gambit drawing grid and numerical calculations to using a software package Efficient called Ansys Fluent by subsidies carried out and the results with the results of a study comparing the temperature of the wall and the heat pipe in all three areas have been analyzed.

Increasing development of industry And keep pace with the rising cost of energy around the world Has meant that engineers are always looking for items The ability have to transfer large amounts of heat in the area of long and low, with a drop in temperature as well as lower power consumption than traditional equipment . Thermosyphon heat pipe type have attracted much attention. The main purpose of this project Evaluate the performance of a particular type of thermosyphon heat pipe with variable conductivity. The heat input to changes in load or temperature evaporation temperature of the evaporator can be fixed. We did this by using the metal balls in the evaporator tube thermosyphon . According to the current situation and said Laboratory equipment was required by the With to provide for measuring The rate of fluid filling tube , We study on heat pipe with variable coefficients The loss and the overall heat transfer coefficient. The results showed that Performance of the heat pipe is different in the thermal load 30, 60, 90, 120 watts per square meter due to changes in the size of the evaporator . The best performance of themosyphon was by comparing the data on the maximum amount of heat load of 120 watts at least during the inactive part of the evaporator between 0 to 1.5 cm.

Thermosyphons are devices used to transfer heat from a hot to a cold source bene ting the eect of gravity. They consist of three main parts, namely, evaporator, condenser and adiabatic section. Working uid absorbs heat from the heat source and delivers it to the condenser section and releases it into the environment. Thermosyphones are able to transfer heat between the heat sources and sinks. Due to the high latent heat of the working uid, thermosyphones can transfer huge amounts of energy. Therefore, they are considered one of the best heat transfer devices. They are widely used in various industrial elds, such as in solar systems, microelectronic devices, CPU cooling and air conditioning. Most researchers in this eld focus only on heat transfer characteristics, and, due to practical considerations, rarely consider their hydrodynamic speci cations. Indeed, the hydrodynamic characteristics of thermosyphones considerably aect their performance. In this paper, the velocity pro le in the liquid phase is determined via a particle image velocimetry technique (PIV). For this purpose, a typical thermosyphon has been designed and constructed with transparent up riser and down-comer sections. In this study, a circular thermosyphon is analyzed and water is used as a working uid in the circular thermosyphon. At the beginning, the velocity eld of the liquid phase is detected in the transparent thermosyphon using a high speed camera and an image processing technique. Subsequently, these pictures are used to generate the velocity pro les and are combined with theoretical analyses to evaluate the performance of the thermosyphon. The results are compared with numerical investigations and show good consistency. The results indicate that the particle image velocimetry (PIV) truly determines the hydrodynamic and thermal characteristics of the thermosyphones. Moreover, in this study, the eect of input heat and the inclination angle of the thermosyphon are investigated numerically. It has been shown that the maximum eciency of thermosyphon is in a horizontal position.

This paper shows the effect of shear stress of liquid-vapor interface with and without mass transfer on thermal performance of a thermosyphon by the integral method. In this analysis, governing equation solved for laminar flow to find velocity profile, thickness of liquid film as well as heat transfer coefficient. In this study, a thermosyphon with 30.5cm length and 2.42cm inner diameter is analyzed. Methanol is used as a working fluid at saturated temperature of 63°C. Results show that the shear stress of liquid-vapor interface decreases the rate of heat transfer.