USING LOOP THERMOSYPHON TO WASTE HEAT REMOVAL FROM POWER ELECTRONIC COMPONENT

Loop thermosyphon is a simple and reliable device providing several times higher heat transfer than convectional coolers used in cooling electronic. The paper deals with the cooling of power electronic component by means of this device. The main object of the paper is design and construction of the device to provide heat removal from the electronic component. Paper describes function principle of loop thermosyphon, testing of the function and measurement of cooling efficiency in dependence on input electric power of the electronic component. The findings from measurement of loop thermosyphon cooling efficiency are compared with natural convective alumina cooler on the end of paper

PRODUCTION OF EMISSIONS DURING COMBUSTION OF DENDROMASS WITH DIFFERENT TYPES OF ADDITIVES

Dendromass remains the largest biomass energy source today. Dendromass has a lot of advantages in comparison with fossil fuels. One important benefit is reduced SO2 and NOx formation through a decrease in fuel bound sulfur and nitrogen respectively. One of applications of dendromass are wood pellets. Using of additives can affect some properties of wood pellets include combustion and production of emissions. In this work were produced wood pellets with additives (kaolin, talc, lime, limestone, dolomite) in 2 % amount in comparison with pellets which are free of additive (reference sample). The effect of various additives to formation of emissions was observed. Experimental measurements have been performed in domestic boiler for combustion of wood pellets with rated power 18 kW. During the measurements were recorded concentrations of following emissions: CO, SO2, NOx, OGC and particulate matters (PM) in the flue gas. The lowest concentrations of CO were recorded in the sample with 2% of kaolin in comparison with reference sample. The highest concentrations of carbon monoxide have been reported in sample with addition of lime. The results of SO2, NOx and OGC production indicate negligible difference, when comparing the reference sample to samples with additives. The highest amount of particulate matter was observed in measurements of lime and limestone. The sample with dolomite has lower concentration of total particulate matter in comparison to reference sample. The results of measurements indicate that the type of additive has a considerable effect on the combustion process and formation of emissions

ASH MELTING TEMPERATURE PREDICTION FROM CHEMICAL COMPOSITION OF BIOMASS ASH

Solid fuels, including biomass, consist of combustible, ash and water. Ash in fuel is result of reaction of minerals presented in the biomass. Minerals and other different substances which form ash got into biomass during growth. Ash is solid residue resulted from the perfect laboratory combustion of fuel. It is composed of minerals that are present in the fuel. Some species of biomass ash have low ash melting temperature and can cause various problems in combustion boilers. Ash slags and sinters can avoid heat transfer in heat exchangers, which can cause corrosion of heat transfer surfaces.Ash melting temperature can be determined on the basis of standard STN ISO 540 in some laboratory. Meltability of ash is characterized by the physical state of the ash, which occurs during the heating process under well-defined conditions in furnace. There exist 4 types of ash melting temperature - Shrinkage temperature (ST), Deformation temperature (DT), Hemisphere temperature (HT) and Flow temperature (FT). Experimental determination of ash melting temperature is quite expensive. In paper is described method of prediction ash melting temperature from known chemical composition of biomass ash. There is proposed mathematic model for determination of all ash melting temperatures. There is need to know the proportion of SiO2, CaO, K2O, MgO and Al2O3 in biomass ash. The mathematical model is relatively accurate with real ash melting temperatures and reaches accuracy about 90 % compared with ash melting temperatures obtained by STN ISO 540 method

THE INFLUENCE OF GRAVITY TO REMOVE WASTE HEAT OF POWER ELECTRONIC COMPONENTS USING LHP

Given the rapid progress in the electronics industry, the thermal management of electronics components becomes an important and serious issue. Natural and forced cooling for heat sink are often deficient. One possibility of heat dissipation for high heat flux is using loop heat pipe. The loop heat pipe (LHP) is a two-phase device with extremely high effective thermal conductivity that utilizes the thermodynamic pressure difference to circulate fluid. It was invented in Russia in the early 1980’s. This work deals with the design of LHP for cooling of Insulated gate bipolar transistor and impact of tilt angle of LHP on temperature of transistor. The maximum temperature of transistor is 100°C. LHP is made of copper pipe. Working fluid is distilled water

THE IMPACT OF LHP POSITION TO REMOVE WASTE HEAT FROM THE POWER COMPONENTS

Given the rapid progress in the electronics industry, the thermal management of electronics components becomes an important and serious issue. Natural and forced cooling are often deficient. One possibility for heat dissipation for high heat flux is using loop heat pipe. A loop heat pipe (LHP) is a two-phase device with extremely high effective thermal conductivity that utilizes pressure difference in wick to circulate working fluid. It was invented in Russia in the early 1980’s. LHP is composed by an evaporator, a condenser, a compensation chamber (reservoir) and a vapor and liquid lines. Only the evaporator and part of the compensation chamber are equipped with a wick structure. The use of the wick structure in the evaporator provides a stable physical interface between the liquid and the vapor phases in the LHP. This work deals with the design of LHP for cooling of Insulated gate bipolar transistor and impact of tilt angle of LHP on temperature of transistor. The LHP position is changed from the vertical position (90°) to the horizontal position (0°) during the measurement. The LHP evaporator is made up with copper pipe and alumina saddle. Inside of the evaporator is wick structure and it is made from copper powder. The condenser is made as a tube heat exchanger. The water temperature for cooling is set at 20°C and it is regulated by a thermostat. The temperatures are measured with the thermocouples. As the working fluid was used distilled water. The maximum permissible temperature of transistor is 100°C

The increase of silver grass ash melting temperature using additives

Some types of biomass have a high content of alkali oxides and salts and, thanks to it they feature a low ash melting temperature which may result in various combustion problems. Slag and sintered particles that are formed prevent the fuel from being supplied, restrict the access of combustion air, heat transfer in the heat exchanger and can cause corrosions. One possibility of increasing the ash melting temperature is to add additives. Some additives can change chemical composition of fuel ash, thus changing also the ash melting temperature. The paper deals with the adding of 2 % additives - kaolin, talc, lime, limestone, dolomite, bentonite to silver grass. The tested additives increased the ash content but they also changed its chemical composition, which resulted in the increase of the ash melting temperature. Best positive results were achieved with kaolin and lime which increased the ash melting temperature by approx 300 degrees C.Web of Science5126525

Experimental measurement, calculation and thermal visualization condenser temperature of cooling device with a heat pipe technology

This work deal with evaluation of condenser temperature by experimental measurement, calculation and thermal visualization of cooling device working with a heat pipe technology. The referred device in the article is cooling device capable transfer high heat fluxes from electric elements to the surrounding. One from many things influenced the heat flux amount transferred from electronic elements through the cooling device to the surrounding is condenser construction, its capacity and option of heat removal. The work contain description, working principle and construction of cooling device. Experimental part describe the measuring method and mathematical calculation to condenser temperature evaluation of cooling device depending on the loaded heat of electronic components in range from 250 to 750 W. The mathematical calculation is based on physical phenomena of boiling, condensation and natural convection heat transfer. The results of experimental measurement and mathematical calculation are verified by thermal imagining of device condenser by IR camera

MEASURING THERMAL PERFORMANCE OF GRAVITATIONAL HEAT PIPES DEPENDING ON THE AMOUNT OF WORKING FLUID

A b s t r a c t This paper deals with an impact of working medium on the performance parameters of the heat pipe. The aim was to find the ideal amount of working fluid used in gravitational heat pipes. For the working medium 96% alcohol was selected

Influence of structural design condensing part of NH

The article describes influence design heat exchangers to efficiency condensation liquid ammonia in the gravitational heat pipe. Analyse adverse factors in the operation and flow of ammonia in heat pipe. Also describes heat transfer characteristics of heat pipe in low-potential geothermal heat transport simulations

Odvádzanie tepla z IGBT prvku slučkovým termosyfónom

Příspěvek se zabývá chlazení výkonových elektronických součástek smyčkovým termosyfónem. Hlavním cílem této práce je návrh a konstrukce zařízení pro zajištění odvodu tepla z elektronických součástek. Článek popisuje princip funkce smyčkového termosyfónu, testování funkce a měření účinnost chlazení v závislosti na vstupní elektrické energie elektronického prvku. V závěru jsou uvedené výsledky z měření účinnosti chlazení IGBT prvku smyčkovým termosifónom ve srovnání s konvekčním chladičem a vizualizace odvodu tepla z IGBT prvku smyčkovým termosyfónom do okolí přirozenou konvekci.The paper deals with the cooling of power electronic component by means of this device. The main object of the paper is design and construction of the device to provide heat removal from the electronic component. Paper describes function principle of loop thermosyphon, testing of the function and measurement of cooling efficiency in dependence on input electric power of the electronic component. The findings from measurement of loop thermosyphon cooling efficiency are compared with natural convective alumina cooler on the end of paper