scholarly journals Establishing Boundary Conditions Considering Influence Factors of the Room Equipped with a Ceiling Radiant Cooling Panel

Energies ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1684 ◽  
Author(s):  
Sang-Hoon Park ◽  
Dong-Woo Kim ◽  
Goo-Sang Joe ◽  
Seong-Ryong Ryu ◽  
Myoung-Souk Yeo ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Boundary Conditions ◽  
Simulation Model ◽  
Influence Factors ◽  
Cooling Capacity ◽  
Heat Transfer Model ◽  
Transfer Model ◽  
Factors Affecting ◽  
Various Boundary Conditions ◽  
Radiant Cooling

The objective of this study is to establish boundary conditions to evaluate the cooling capacity of the Cooling Radiant Ceiling Panel (CRCP) considering the environment of a room equipped with the CRCP. The current study investigated the boundary conditions and derivation techniques from previous studies. Based on the results of the analysis, a heat transfer model was derived for a room fitted with CRCP. In addition, the heat transfer model was used to derive the factors affecting the cooling capacity of the CRCP and each factor was simulated and verified through this model. The effects of these factors on the capacity of the CRCP was established by using various boundary conditions. To verify the validity of the simulation model, the experimental results were compared with the cooling capacity for a specific case. As a result, it was established that even for the same panel, there was a variance in the cooling capacity of the CRCP based on the boundary conditions and that the influence of the surface exposed to the outdoors had more implications. Consequently, this study presents the influence factors to be considered when designing CRCP.

CFD Analysis of the EGR Cooler’s Heat Transfer Performance

2014 ◽  
Vol 889-890 ◽  
pp. 309-315
Author(s):  
Zhi‘en Liu ◽  
Yu Xu
Keyword(s):  
Heat Transfer ◽  
Boundary Conditions ◽  
Cfd Simulation ◽  
Exchange Process ◽  
Decomposition Methods ◽  
Heat Transfer Model ◽  
Transfer Model ◽  
Middle Portion ◽  
Model Based ◽  
Egr Cooler

A CFD simulation of the performance of an EGR cooler was carried out. Considering the differences between the heat exchange process of its inlet portion, middle portion and outlet portion, this simulation divided the model into three parts and analyzed them in turn. For the inlet and outlet portion, the convective heat transfer model was applied; while for the middle portion, an air-solid-liquid three-phase heat transfer model, based on strong coupling was extracted. According to the geometry continuity of the model, the boundary conditions of the middle portion was determined by the simulation result of the inlet portion, and the boundary conditions of the outlet portion was determined by the simulation result of the middle portion. Ultimately, we can gain the overall temperature distribution of the EGR cooler under the premise of ensuring the accuracy of the heat transfer model and minimizing the computation. This model based on decomposition methods was applied to the temperature field simulation under different EGR cooler rate and the simulation results were in good agreement with the experimental results.

A Heat Transfer Model Based on Finite Difference Method for Grinding

2011 ◽  
Vol 133 (3) ◽  
Author(s):  
Bin Shen ◽  
Albert J. Shih ◽  
Guoxian Xiao
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Boundary Conditions ◽  
Contact Zone ◽  
Convection Heat Transfer ◽  
Heat Transfer Model ◽  
Transfer Model ◽  
Convection Heat ◽  
Convection Heat Transfer Coefficient ◽  
Mql Grinding

A heat transfer model for grinding has been developed based on the finite difference method (FDM). The proposed model can solve transient heat transfer problems in grinding, and has the flexibility to deal with different boundary conditions. The model is first validated by comparing it with the traditional heat transfer model for grinding which assumes the semiinfinite workpiece size and adiabatic boundary conditions. Then it was used to investigate the effects of workpiece size, feed rate, and cooling boundary conditions. Simulation results show that when the workpiece is short or the feed rate is low, transient heat transfer becomes more dominant during grinding. Results also show that cooling in the grinding contact zone has much more significant impact on the reduction of workpiece temperature than that in the leading edge or trailing edge. The model is further applied to investigate the convection heat transfer at the workpiece surface in wet and minimum quantity lubrication (MQL) grinding. Based on the assumption of linearly varying convection heat transfer coefficient in the grinding contact zone, FDM model is able to calculate convection coefficient from the experimentally measured grinding temperature profile. The average convection heat transfer coefficient in the grinding contact zone was estimated as 4.2 × 105 W/m2-K for wet grinding and 2.5 × 104 W/m2-K for MQL grinding using vitrified bond CBN wheels.

scholarly journals Investigation on the Performance Enhancement and Emission Reduction of a Biodiesel Fueled Diesel Engine Based on an Improved Entire Diesel Engine Simulation Model

Processes ◽  
2021 ◽  
Vol 9 (1) ◽  
pp. 104
Author(s):  
Weigang Yu ◽  
Zhiqing Zhang ◽  
Bo Liu
Keyword(s):  
Heat Transfer ◽  
Diesel Engine ◽  
Simulation Model ◽  
Combustion Process ◽  
Injection Rate ◽  
Heat Transfer Model ◽  
Injection System ◽  
Biodiesel Fuel ◽  
Transfer Model ◽  
Load Characteristics

In order to improve the efficiency of the diesel engine and reduce emissions, an improved heat transfer model was developed in an AVL-BOOST environment which is a powerful and user-friendly software for engine steady-state and transient performance analysis. The improved heat transfer model considers the advantages of the Woschni1978 heat transfer model and Honhenberg heat transfer model. In addition, a five-component biodiesel skeletal mechanism containing 475 reactions and 134 species was developed to simulate the fuel spray process and combustion process since it contained methyl linolenate, methyl linoleate, methyl oleate, methyl stearate, and methyl palmitate, which are a majority component in most biodiesel. Finally, the propulsion and load characteristics of a diesel engine fueled with biodiesel fuel were investigated by the improved heat transfer model in term of power, brake specific fuel consumption (BSFC), soot and NOx emissions. Similarly, the effects of the fuel injection rate on the diesel engine’s characteristic fueled with biodiesel was studied. The result showed that the errors between experiment and simulation were less than 2%. Thus, the simulation model could predict the propulsion and load characteristics of the diesel engine. The nozzle diameter, injection pressure, and injection advance angle are significant to the injection system. Thus, it is very important to choose the injection rate reasonably.

Computer Assisted Simulation Model for Cryoablation of Prostate Cancer Including the Possible Injury of Rectum

2010 ◽  
Author(s):  
Chih-Wei Chen ◽  
Hong-Sen Kou ◽  
Hsueh-Erh Liu ◽  
Cheng-Keng Chuang ◽  
Li-Jen Wang
Keyword(s):  
Prostate Cancer ◽  
Heat Transfer ◽  
Simulation Model ◽  
Three Dimensional ◽  
Heat Transfer Model ◽  
Transient Temperature ◽  
Thermal Calculation ◽  
Computer Assisted ◽  
Transfer Model ◽  
Time Duration

This study is to establish a preliminary computer assisted simulation model for cryoablation of a prostate cancer. It is hoped that the results from this study can supply valuable data for the clinician to refer to before a real cryosurgery or cryotherapy. In order to reach the goal of real implementation, a radiologist and an urologist in a medical center in addition to the engineering specialist from the university participated in this interdisciplinary research program. Firstly, hundreds of the two-dimensional medical imaging photos for the patient are obtained from the magnetic resonance imaging (MRI) in the imaging department of hospital. Through the imaging reconstructive software, these photos are trimmed into building a three-dimensional solid modeling. In this step, the urethra, bladder, prostate and rectum are segmented separately into an engineering graphic solid model with high resolution. Secondly, the number of probes, the position of each probe, and the operating time duration of each probe are determined in advance according to the clinical experience from a surgeon. Meanwhile, these data are transferred into the software package of thermal calculation for numerical simulations. Thirdly, the energy equation in the commercial software is modified to behave bio-heat transfer model by the input of user subroutines. Moreover, the occurrence of phase change during some specified temperature range and the latent heat of fusion are also incorporated into bio-heat transfer model to simulate the clinical situation for cryoablation of prostate cancer. In the simulation model, the three-dimensional transient temperature distributions based on cryosurgery for prostate cancer have been demonstrated precisely. The cryoprobes with various freezing time are considered to observe the temperature distribution. In addition, the frozen rectum is displayed in a region enclosed by a critical isotherm of 0°C. The simulated results for cryosurgery of prostate cancer can be supplied for practicing physicians as reference to greatly improve the effectiveness of cryosurgery.

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