• Title/Summary/Keyword: Heat exchanger design

Search Result 684, Processing Time 0.024 seconds

Cooling Performance Study of a Impinging Water Jet System with Heat Sink for High Power LEDs (분사냉각모듈 내에 부착된 히트싱크에 따른 고출력 LED의 냉각성능에 관한 연구)

  • Ku, G.M.;Kim, K.;Park, S.H.;Choi, S.D.;Heo, J.W.
    • Journal of the Korean Society of Manufacturing Process Engineers
    • /
    • v.12 no.6
    • /
    • pp.152-158
    • /
    • 2013
  • The purpose of this study is to investigate cooling performance of high power LEDs from 100 to 200 W class by using a jet impingement cooling module. The numerical analysis of forced convection cooling inside cooling module is carried out using a multi-purpose CFD software, FLUENT 6.3. In the experiments, the LED cooling system consists of jet impingement module, heat exchanger, water reservoir, and pump. In the present study, the cooling performance of jet impingement cooling module is investigated to determine the effect of the heat sink types on the impinging surface, the space and length of fins. Numerical and experimental studies show the reasonable agreement of LED metal PCB temperature between those results and give the optimized design parameters such as the space of fin and the length of fin. Also, the pin fin type of heat sink is found to be more efficient than the plate type heat sink in jet impingement cooling.

Recent Progress in Air-Conditioning and Refrigeration Research : A Review of Papers Published in the Korean Journal of Air-Conditioning and Refrigeration Engineering in 2013 (설비공학 분야의 최근 연구 동향 : 2013년 학회지 논문에 대한 종합적 고찰)

  • Lee, Dae-Young;Kim, Sa Ryang;Kim, Hyun-Jung;Kim, Dong-Seon;Park, Jun-Seok;Ihm, Pyeong Chan
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
    • /
    • v.26 no.12
    • /
    • pp.605-619
    • /
    • 2014
  • This article reviews the papers published in the Korean Journal of Air-Conditioning and Refrigeration Engineering during 2013. It is intended to understand the status of current research in the areas of heating, cooling, ventilation, sanitation, and indoor environments of buildings and plant facilities. Conclusions are as follows. (1) The research works on the thermal and fluid engineering have been reviewed as groups of fluid machinery, pipes and relative parts including orifices, dampers and ducts, fuel cells and power plants, cooling and air-conditioning, heat and mass transfer, two phase flow, and the flow around buildings and structures. Research issues dealing with home appliances, flows around buildings, nuclear power plant, and manufacturing processes are newly added in thermal and fluid engineering research area. (2) Research works on heat transfer area have been reviewed in the categories of heat transfer characteristics, pool boiling and condensing heat transfer and industrial heat exchangers. Researches on heat transfer characteristics included the results for general analytical model for desiccant wheels, the effects of water absorption on the thermal conductivity of insulation materials, thermal properties of Octadecane/xGnP shape-stabilized phase change materials and $CO_2$ and $CO_2$-Hydrate mixture, effect of ground source heat pump system, the heat flux meter location for the performance test of a refrigerator vacuum insulation panel, a parallel flow evaporator for a heat pump dryer, the condensation risk assessment of vacuum multi-layer glass and triple glass, optimization of a forced convection type PCM refrigeration module, surface temperature sensor using fluorescent nanoporous thin film. In the area of pool boiling and condensing heat transfer, researches on ammonia inside horizontal smooth small tube, R1234yf on various enhanced surfaces, HFC32/HFC152a on a plain surface, spray cooling up to critical heat flux on a low-fin enhanced surface were actively carried out. In the area of industrial heat exchangers, researches on a fin tube type adsorber, the mass-transfer kinetics of a fin-tube-type adsorption bed, fin-and-tube heat exchangers having sine wave fins and oval tubes, louvered fin heat exchanger were performed. (3) In the field of refrigeration, studies are categorized into three groups namely refrigeration cycle, refrigerant and modeling and control. In the category of refrigeration cycle, studies were focused on the enhancement or optimization of experimental or commercial systems including a R410a VRF(Various Refrigerant Flow) heat pump, a R134a 2-stage screw heat pump and a R134a double-heat source automotive air-conditioner system. In the category of refrigerant, studies were carried out for the application of alternative refrigerants or refrigeration technologies including $CO_2$ water heaters, a R1234yf automotive air-conditioner, a R436b water cooler and a thermoelectric refrigerator. In the category of modeling and control, theoretical and experimental studies were carried out to predict the performance of various thermal and control systems including the long-term energy analysis of a geo-thermal heat pump system coupled to cast-in-place energy piles, the dynamic simulation of a water heater-coupled hybrid heat pump and the numerical simulation of an integral optimum regulating controller for a system heat pump. (4) In building mechanical system research fields, twenty one studies were conducted to achieve effective design of the mechanical systems, and also to maximize the energy efficiency of buildings. The topics of the studies included heating and cooling, HVAC system, ventilation, and renewable energies in the buildings. Proposed designs, performance tests using numerical methods and experiments provide useful information and key data which can improve the energy efficiency of the buildings. (5) The field of architectural environment is mostly focused on indoor environment and building energy. The main researches of indoor environment are related to infiltration, ventilation, leak flow and airtightness performance in residential building. The subjects of building energy are worked on energy saving, operation method and optimum operation of building energy systems. The remained studies are related to the special facility such as cleanroom, internet data center and biosafety laboratory. water supply and drain system, defining standard input variables of BIM (Building Information Modeling) for facility management system, estimating capability and providing operation guidelines of subway station as shelter for refuge and evaluation of pollutant emissions from furniture-like products.

Basic Design and Sensitivity Analysis of 3 MWth Chemical Looping Combustion System for LNG Combustion and Steam Generation (LNG 연소 및 스팀생산을 위한 3 MWth 급 매체순환연소 시스템의 기본설계 및 민감도 분석)

  • RYU, HO-JUNG;NAM, HYUNGSEOK;HWANG, BYUNG WOOK;KIM, HANA;WON, YOOSEOB;KIM, DAEWOOK;KIM, DONG-WON;LEE, GYU-HWA;BAEK, JEOM-IN
    • Journal of Hydrogen and New Energy
    • /
    • v.32 no.5
    • /
    • pp.374-387
    • /
    • 2021
  • Basic design of 3 MWth chemical looping combustion system for LNG combustion and steam generation was conducted based on the mass and energy balance and the previous reactivity test results of oxygen carrier particles. Process configuration including fast fluidized bed (air reactor), loop seal and bubbling fluidized bed (fuel reactor) was confirmed and their dimensions were determined by mass balance. Then, the external fluidized bed heat exchanger (FBHE) was adopted based on the energy balance to extract heat from the system. The optimum reactor design and operating condition was confirmed with sensitivity analysis by modifying system configuration based on the mass and energy balance.

An Influence of Groundwater Flow on Performance of Closed Borehole Heat Exchangers (Part-2) (지하수류가 밀폐형 천공 지중 열교환기 성능에 미치는 영향(2))

  • Hahn, Jeongsang;Kiem, Youngseek;Lee, Juhyun;Lee, Byoungho;Hahn, Chan
    • Journal of Soil and Groundwater Environment
    • /
    • v.21 no.6
    • /
    • pp.114-127
    • /
    • 2016
  • An increase of groundwater flux in BHE system creates that ground temperature (locT) becomes lower in summer and higher in winter time. In other words, it improves significantly the performance of BHE system. The size of thermal plume made up by advection driven-flow under the balanced energy load is relatively small in contrast to the unbalanced energy load where groundwater flow causes considerable change in the size of thermal plume as well ground temperature. The ground temperatures of the up gradient and down gradient BHEs under conduction only heat transport are same due to no groundwater flow. But a significant difference of the ground temperature is observed between the down gradient and up gradient BHE as a result of groundwater flow-driven thermal interference took placed in BHE field. As many BHEs are designed under the obscure assumption of negligible groundwater flow, failure to account for advection can cause inefficiencies in system design and operation. Therefore including groundwater flow in the design procedure is considered to be essential for thermal and economic sustain ability of the BHE system.

Optimization Design of Commercial Large Gas Oven Systems (상업용 대형 가스오븐 시스템의 최적 설계)

  • Kim, Do-Hyun;Yu, Byeonghun;Kum, Sungmin;Lee, Chang-Eon
    • Journal of Energy Engineering
    • /
    • v.25 no.2
    • /
    • pp.21-28
    • /
    • 2016
  • This research was conducted for the optimal design of large commercial gas oven system. Equivalent ratio was determined through a numerical analysis and experiments on the combustion condition of the combustor. After reviewing the supply capacity of burner(20,000 kcal) and control method of convection fan, two types of heat exchangers designed. In order to maintain a uniform temperature inside the oven is required convection fan braking system. The center temperature in the oven rises more rapidly when the convectional fan is rotated in the counterclockwise direction than the counter-clockwise direction. And The efficiency of the system by installing a large heat transfer area was higher.

Design Optimization of Heat Exchangers for Solar-Heating Ocean Thermal Energy Conversion (SH-OTEC) Using High-Performance Commercial Tubes (고성능 상용튜브를 사용한 태양열 가열 해양온도차발전용 열교환기 설계 최적화)

  • Zhou, Tianjun;Nguyen, Van Hap;Lee, Geun Sik
    • Transactions of the Korean Society of Mechanical Engineers B
    • /
    • v.40 no.9
    • /
    • pp.557-567
    • /
    • 2016
  • In this study, the optimal design of heat exchangers, including the evaporator and condenser of a solar-heating ocean thermal energy conversion (SH-OTEC), is investigated. The power output of the SH-OTEC is assumed to be 100 kW, and the SH-OTEC uses the working fluid of R134a and high-performance commercial tubes. The surface heat transfer area and the pressure drop were strongly dependent on the number of tubes, as well as the number of tube passes. To solve the reciprocal tendency between the heat transfer area and pressure drop with respect to the number of tubes, as well as the number of tube passes, a genetic algorithm (GA) with two objective functions of the heat transfer area (the capital cost) and operating cost (pressure drop) was used. Optimal results delineated the feasible regions of heat transfer area and operating cost with respect to the pertinent number of tubes and tube passes. Pareto fronts of the evaporator and condenser obtained from multi-objective GA provides designers or investors with a wide range of optimal solutions so that they can select projects suitable for their financial resources. In addition, the surface heat transfer area of the condenser took up a much higher percentage of the total heat transfer area of the SH-OTEC than that of the evaporator.

Prediction and Experiment of Pressure Drop of R22 and R134a on Design Conditions of Condenser (응축기의 설계조건에서 R22와 R134a의 압력강하 예측 및 실험)

  • Kang, Shin-Hyung;Byun, Ju-Suk;Kim, Chang-Duk
    • Journal of Energy Engineering
    • /
    • v.15 no.4 s.48
    • /
    • pp.243-249
    • /
    • 2006
  • An experimental study on the refrigerant-side pressure drop of slit fin an tube heat exchanger has been carried out. A comparison was made between the predictions of previously proposed empirical correlations and experimental data for the pressure drop on design conditions of condenser in micro-fin tube for R22 and Rl34a. Experiments were carried out under the conditions of inlet refrigerant temperature of $60^{\circ}C$ and mass fluxes varying from $150\;to\;250\;kg/m^{2}s$ for R22 and Rl34a. The inlet air conditions are dry bulb temperature of $35^{\circ}C$, relative humidity of 40% and air velocity varying from 0.68 to 1.43 m/s. Experiments show that pressure drop for R134a was $22{\sim}22.6%$ higher than R22 for the degree of subcooling $5^{\circ}C$ For the mass fluxes of $200{\sim}250\;kg/m^{2}s$, the deviation between the experimental and predicted values for the pressure drop was less than ${\pm}20%$ for R22 and Rl34a.

Investigation of FIV Characteristics on a Coaxial Double-tube Structure (동심축 이중관 구조에서 유동기인진동 특성 고찰)

  • Song, Kee-Nam;Kim, Yong-Wan;Park, Sang-Chul
    • Transactions of the Korean Society of Mechanical Engineers A
    • /
    • v.33 no.10
    • /
    • pp.1108-1118
    • /
    • 2009
  • A Very High Temperature Gas Cooled Reactor (VHTR) has been selected as a high energy heat source of the order of $950^{\circ}C$ for nuclear hydrogen generation, which can produce hydrogen from water or natural gas. A primary hot gas duct (HGD) as a coaxial double-tube type cross vessel is a key component connecting a reactor pressure vessel and an intermediate heat exchanger in the VHTR. In this study, a structural sizing methodology for the primary HGD of the VHTR is suggested in order to modulate a flow-induced vibration (FIV). And as an example, a structural sizing of the horizontal HGD with a coaxial double-tube structure was carried out using the suggested method. These activities include a decision of the geometric dimensions, a selection of the material, and an evaluation of the strength of the coaxial double-tube type cross vessel components. Also in order to compare the FIV characteristics of the proposed design cases, a fluid-structure interaction (FSI) analysis was carried out using the ADINA code.

Field study of 5kW class PEMFC system (5kW급 고분자전해질 연료전지 시스템 실증연구)

  • Lee, SooJae;Choi, Dae Hyun;Jun, HeeKwon
    • 한국신재생에너지학회:학술대회논문집
    • /
    • 2011.05a
    • /
    • pp.87.1-87.1
    • /
    • 2011
  • The residential Fuel Cell system has high efficiency of 85% with transferring natural gas to electrical power and heat, directly and it is a friendly environmental new technology in that $CO_2$ emission can reduce 40% compared with conventional power generator and boiler. The residential fuel cell system consists of two main parts which have electrical and hot storage units. The electrical unit contains a fuel processor, a stack, an inverter, a control unit and balance of plant(BOP), and the cogeneration unit has heat exchanger, hot water tank, and auxiliaries. 5kW class fuel process was developed and tested from 2009, it was evaluated for long-term durability and reliability test including with improvement in optimal operation logic. Stack development was crried out through improvement of design and evaluation protocol. Development of system controller was successfully accomplished through strenuous efforts and original control logic was optimized in 5kW class PEMFC system. In addition, we have been focused on development of system process and assembly technology, which bring about excellent improvement of reliability of system. The 5kW class PEMFC system was operated under dynamic conditions for 1,000 hours and it showed a good performance of total efficiency and durability.

  • PDF

Study on cement-based grout for closed-loop vertical ground heat exchanger (수직 밀폐형 지중 열교환기 뒤채움재로서 시멘트 그라우트의 적용성 검토)

  • Park, Moon-Seo;Wi, Ji-Hae;Lee, Chul-Ho;Lee, Kang-Ja;Choi, Hang-Seok
    • Proceedings of the Korean Geotechical Society Conference
    • /
    • 2010.03a
    • /
    • pp.615-624
    • /
    • 2010
  • In this paper, the applicability of cement grout has been studied as an alternative to bentontite grout to backfill ground heat exchangers. To provide an optimal mixture design, the groutabilty and thermal conductivity of cement grouts with various mixture ratios were experimentally evaluated and compared. The unconfined compression strength of cement grout specimen was measured, which are exposed to cyclic temperature variation ranging from $50^{\circ}C$ to $-5^{\circ}C$. In addition, the integrity of the interface between circulating HDPE pipes and cement grout by performing equivalent hydraulic conductivity tests, in which a pipe locates at the center of the specimen.

  • PDF