• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.14 no.6
• /
• pp.525-531
• /
• 2002

The effects of different surface hydrophilicity on frosting and defrosting characteristic were experimentally investigated. Mass of frost and water hold-up was measured. Results showed that no significant difference in the frost mass was found between the two different surfaces while the water hold-up of heat exchanger court be reduced by the enhancement of surface hydrophilicity. Also, the defrosting efficiency m hydrophilic surface was improved by 76%. It was expected that hydrophilic heat exchanger could provide the improvements in both thermal-hydraulic performances and system reliability during frost/defrost operating in refrigeration systems.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.23 no.7
• /
• pp.477-482
• /
• 2011

In the present study, the performance characteristics of the heat pump chiller under heating conditions were experimentally investigated. Capacity, input power and COP under overload, frost and defrost conditions were obtained. The experimental data for the heat pump chiller were measured using the air-enthalpy calorimeter and the constant temperature water bath. At overload condition, the heating capacity and COP increase about 25.7% and 19.1%, respectively. The variations of the evaporator, the compressor outlet and the condenser temperature were obtained under frost and defrost conditions. The frost and defrost period of the heat exchanger decreases about 36.0~56.1%.

• Journal of Auto-vehicle Safety Association
• /
• v.16 no.2
• /
• pp.44-50
• /
• 2024

The windshield of a vehicle plays an important role in ensuring driver safety and maintaining visibility. To prevent issues such as frost and mist from occurring inside and outside the vehicle, research related to the defrosting performance of the windshield is being conducted. Evaluating defrosting performance requires accurate thermal flow analyses. Therefore, in this study, a defrosting duct was constructed within a chamber at an actual vehicle scale to evaluate its performance, and a finite element model was developed and verified. To evaluate defrosting performance, the temperature of the windshield was measured under condition with a mass flow rate of 0.1 kg/s, which corresponds to that of a typical midsize vehicle. A total of 45 thermocouples were arranged at equal intervals of 9 widths and 5 lengths on the windshield to measure the temperature and compare it with the temperature predicted through finite element analysis. A volume grid was created in the main flow area to ensure accurate thermal flow analyses, and a prism layer was added at the interface between the windshield and fluid. In total, 6 million grid systems were formed. Comparing the temperature fields of the experimental results and the finite element analysis results confirmed a similar defrosting pattern, with an average temperature difference of 0.64K.

• Proceedings of the KSME Conference
• /
• 2008.11b
• /
• pp.2454-2459
• /
• 2008

The objective of this paper is to find out the most effective injection angle for the purpose of deicing through SC/Tetra, a commonly used CFD software. Nowadays, vehicles are developed giving priority to an improved interior which emphasizes a pleasant environment and thermal comfort without decreasing the basic performance. Clear visibility is one of the most important phenomenon. The primary factors which affect the efficiency of deicing are 3D geometry of Defrost Nozzle, the inlet velocity and temperature of the flow and the injection angle. However in this paper, all these parameters are optimized by changing the injection angle. A wide range of injection angle from 5 degree to 50 degree have been considered for analysis. A very good defrosting performance has been achieved with 45 degree injection angle which can satisfy the condition of NHTSA.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.20 no.12
• /
• pp.789-794
• /
• 2008

Recently, much attention has been paid in the field of defrosting because clear windshield in vehicle without effecting the thermal comfort is realized essentially. Then in winter, defrosting performance is one of the important factors in vehicle design to make certain driver's view. In this study, the velocity profile, temperature distribution and frost melting pattern on the windshield screen have been predicted in three dimensional geometry of an automobile interior. Numerical analyses predict a detailed description of fluid flow and temperature patterns on the inside windshield screen, utilizing the flow through defroster nozzle. Numerical prediction established a good defrosting performance with the standard distance ratio and the defroster nozzle angle ranging from $30^{\circ}$ to $40^{\circ}$, which satisfy the condition of National Highway Traffic Safety Administration (NHTSA) completely.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.26 no.2
• /
• pp.72-78
• /
• 2014

In a cold chain, the refrigerator is also employed for defrosting, by using an electric heater, which consumes 15% of the power for the system operation. In this study, the condensation heat of the refrigerant was suggested as the heat source of defrosting heat, instead of that from an electric defrost heater. The heat for defrosting was stored to a phase change material (PCM, NMP : $52^{\circ}C$) in thermal storage, and was periodically supplied to the evaporator by a circulation loop of brine. As a result, a defrost time by the PCM was obtained that was less than or equal to that by the electric heater. Moreover, power consumption during defrosting was saved by up to 99% of that of the electric heater.

• Journal of the korean Society of Automotive Engineers
• /
• v.9 no.3
• /
• pp.46-54
• /
• 1987

자동차의 외형을 설계하는 과정에서 미적인 관점을 떠나 역학적으로 고려할 때에는 공기역학이 매우 중요하게 된다. 이 분야에서 연구하는 전문가에게는 잘 알려진 내용이 될지는 모르겠으나 자동차의 설계 및 개발에 종사하는 일반연구자에게는 공기역학에 관한 문헌 및 전문서적 또한 주 위에서 쉽게 얻을 수는 있으나 부담없이 인식되기에는 그리 쉬운 일은 아니다. 이와 관련하여 Car Stying Volume 50+1/2의 별책으로 간행된 특집호에 여러 가지 흥미있는 내용이 기술 설명 되어 있다. 이는 1985년 발행되었으며 일본자동차연구소에 재직중인 무능진리씨가 해설하였다. 이후 본 내용은 여기서 발췌함을 밝혀둔다. 자동차에 관한 공기역확은 주로 다음과 같은 성능 향상을 위하여 필요하다. (1) 주행연료비 절약 (2) 최고속도의 향상 (3) 고속주행시 조종안정성의 향상 (4) 횡풍에서 주행안전성 향상 (5) 엔진이나 제동장치 등의 냉각성능 향상 (6) 바람에 의한 소음의 감소 (7) 환기성능의 향상 (8) 제상성능의 향상 (9) 공기 조화성능의 향상 (10) 먼지 또는 오물의 부착방지 및 억제 (11) 창문 와이퍼의 작동 등이다.

• Proceedings of the Korean Society for Agricultural Machinery Conference
• /
• 1999.07a
• /
• pp.104-111
• /
• 1999

증기압축식 열펌프시스템은 그림 1에 나타난 바와 같이 증발기에서의 흡열과 응축기의 방열을 냉난방에 이용할 수 있으며, 공기를 열원으로 할 때는 공기 중 저밀도의 에너지를 고밀도의 에너지로 전환하여 이용할 수 있으며 지중 온도의 연중변화가 적은 점을 이용하여 지열을 열원으로 할 때는 공기를 열원으로 할 경우에 필요한 제상 장치(defrost cycle)가 필요 없게 되고, 압축기 부하도 줄어들게 되어 열펌프 수명이 길어지게 되며 경제성을 확보할 수 있을 것으로 기대된다. (중략)

• 한국전산유체공학회:학술대회논문집
• /
• 2001.05a
• /
• pp.176-180
• /
• 2001

For windshield defrosting, flow analysis of inner room(vehicle) and heat conduction on the windshield surface are undertaken. Simulation for defrosting enthalpy method is usedand verification of heat and fluid flow analysis for room is done in cavity flow. The defrosting process is three dimensional phenomena and phase is changing. The result of defrosting analysis are well presenting the phase change and these results offer basic design data for defrosting phenomena.

• Proceedings of the SAREK Conference
• /
• 2005.06a
• /
• pp.37-37
• /
• 2005