The Experts below are selected from a list of 60366 Experts worldwide ranked by ideXlab platform
Changmi Zhang - One of the best experts on this subject based on the ideXlab platform.
-
the development and performance of the high power led Radiator
International Journal of Thermal Sciences, 2017Co-Authors: Mimi Wang, Hanzhong Tao, Zishuai Sun, Changmi ZhangAbstract:Abstract The performance of a kind of pure aluminum heat sink with radicalized straight fins and a kind of aluminum heat sink with heat pipe are investigated through numerical simulation method. Based on the correctness of numerical simulation model verified by the experiment, the optimal design is preceded. The correlations for Nu without and with heat pipe are obtained. Results show that the junction temperature of LED components is efficiently reduced by raising the Radiator height (100–200 mm), increasing the number of fins (16–32), increasing the fin height respectively and the limitations are strengthened at the same time. The influence of fin thickness considered in this paper on Nusselt number of the Radiator is less than 1%. By the introduction of the heat pipe, the equivalent coefficient of rolled aluminum heat pipe composite Radiator fin upper part increased from 70.8% to 73.1%, temperature difference between the top and bottom fins is reduced, heat dissipation is strengthened. At the same time, the increase of the length of heat pipe Radiator is favorable to the heat dissipation of Radiators and the reduction in Radiators weight. Those all provide the theoretical basis for the design and prioritization of high-power LED module Radiator.
Jarek Kurnitski - One of the best experts on this subject based on the ideXlab platform.
-
experimental analysis of emission efficiency of parallel and serial connected Radiators in en442 test chamber
Applied Thermal Engineering, 2018Co-Authors: Karlvillem Vosa, Andrea Ferrantelli, Tuule Mall Kull, Jarek KurnitskiAbstract:Abstract In the wide context of energy performance, the design of standard Radiators has shown a large improvement in the past decades. Nevertheless, it is still necessary to achieve better understanding of the Radiators emission losses. We conduct measurements of temperature and heat output of different types of emitters in a test chamber of the standard EN 442-2, aiming to quantify the emission efficiency differences of the Radiators studied. We find that in the absence of ventilation, the air stratification is relevant and can explain the heat output differences between repeated tests of the same Radiator. Moreover, correlation curves are derived between relative heat output and radiative component, and between heat output and air and operative temperature difference. Our detailed analysis shows that thermal comfort is more easily achieved with 11-type Radiators, due to the bigger panel surface area, and with 22-type serial-connected Radiators, due to their higher front surface panel temperature. From the measured data we derive the ratio of surface to total thermal resistance of the Radiator, and the convective heat transfer coefficient dependency on the room geometry. While the majority of our results apply strictly to the EN442 test chamber, these can be used for the application to an ordinary room.
Mimi Wang - One of the best experts on this subject based on the ideXlab platform.
-
the development and performance of the high power led Radiator
International Journal of Thermal Sciences, 2017Co-Authors: Mimi Wang, Hanzhong Tao, Zishuai Sun, Changmi ZhangAbstract:Abstract The performance of a kind of pure aluminum heat sink with radicalized straight fins and a kind of aluminum heat sink with heat pipe are investigated through numerical simulation method. Based on the correctness of numerical simulation model verified by the experiment, the optimal design is preceded. The correlations for Nu without and with heat pipe are obtained. Results show that the junction temperature of LED components is efficiently reduced by raising the Radiator height (100–200 mm), increasing the number of fins (16–32), increasing the fin height respectively and the limitations are strengthened at the same time. The influence of fin thickness considered in this paper on Nusselt number of the Radiator is less than 1%. By the introduction of the heat pipe, the equivalent coefficient of rolled aluminum heat pipe composite Radiator fin upper part increased from 70.8% to 73.1%, temperature difference between the top and bottom fins is reduced, heat dissipation is strengthened. At the same time, the increase of the length of heat pipe Radiator is favorable to the heat dissipation of Radiators and the reduction in Radiators weight. Those all provide the theoretical basis for the design and prioritization of high-power LED module Radiator.
Masoud Afrand - One of the best experts on this subject based on the ideXlab platform.
-
numerical study on thermal performance of an air cooled heat exchanger effects of hybrid nanofluid pipe arrangement and cross section
Energy Conversion and Management, 2018Co-Authors: Ali Karimi, Masoud AfrandAbstract:Abstract This study is a numerical investigation of a heat exchanger under external flow. Temperature variable properties are used to solve the governing equations. Air is selected as an external fluid and water and MgO-MWCNTs/EG hybrid nanofluid are selected as Radiator fluid. In this paper, the efficiency of the horizontal and vertical Radiator are studied using experimental data for thermo-physical properties of MgO-MWCNTs/EG Nanofluid. Then, tubes with circular and elliptic sections are investigated for different flows, inlet temperatures and concentrations. The pressure drop and Nusselt number for each simulation are analyzed. Results are presented in terms of temperature distribution, pressure drop, Nusselt number and their sensitivity analysis for different states. The results indicate that Radiators with vertical tubes have better efficiency up to 10% than Radiators with horizontal tubes. In addition, heat exchangers with circular pipes have 25% lower pressure drop and those with elliptical tubes had 10% higher Nusselt number. The finding shows that an increase in the Nano-fluid concentration improves the Nusselt number and increases the pressure drop.
Damian Piotr Muniak - One of the best experts on this subject based on the ideXlab platform.
-
The Sizing of Surface Radiators
Radiators in Hydronic Heating Installations, 2017Co-Authors: Damian Piotr MuniakAbstract:The sizing of surface, i.e. underfloor, wall and ceiling Radiators is carried out with the same initial condition as in the case of convector Radiators. Like a classical convector Radiator, the surface Radiator has to be selected in a manner that ensures the required heat output for design conditions, calculated according to [1]. There are, however, a few differences. In the first place, in the case of surface Radiators the β correction factors are not taken into consideration in the form which is typical of convector Radiators because the variant of the device location, screening, etc. is not defined.
-
Radiators in Hydronic Heating Installations - Radiators in Hydronic Heating Installations
Studies in Systems Decision and Control, 2017Co-Authors: Damian Piotr MuniakAbstract:This book addresses key design and computational issues related to Radiators in hydronic heating installations. A historical outline is included to highlight the evolution of Radiators and heating technologies. Further, the book includes a chapter on thermal comfort, which is the decisive factor in selecting the ideal heating system and Radiator type. The majority of the book is devoted to an extensive discussion of the types and kinds of Radiators currently in use, and to identifying the reasons for the remarkable diversity of design solutions. The differences between the solutions are also addressed, both in terms of the effects of operation and of the thermal comfort that needs to be ensured. The book then compares the advantages and disadvantages of each solution, as well as its potential applications. A detailed discussion, supported by an extensive theoretical and mathematical analysis, is presented of the computational relations that are used in selecting the Radiator type. The dynamics of Radiator heat output regulation are also covered, with particular emphasis on underfloor-surface Radiators, for which this aspect is particularly important. The book closes with a chapter presenting computational examples. It includes numerous examples of calculations for all essential thermal parameters of Radiator operation in heating installations
