• Journal of Power System Engineering
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• v.17 no.2
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• pp.87-94
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• 2013

Applicability of organic Rankine cycle for a passenger car with 3.5 L gasoline engine to convert low grade waste heat to useful shaft power has been numerically studied. Working fluid is R134a, and the Rankine cycle is composed of boiler for recovering engine cooling water heat, super heater for recovering exhaust gas heat, scroll expander for converting waste heat to shaft power, condenser for heat emission, internal heat exchanger, and feed pump. Assuming efficiencies of 90% for the heat exchangers, 75% for the scroll expander, and 80% for the feed pump, the Rankine cycle efficiency of 5.53% was calculated at the vehicle speed of 120 km/hr. Net expander shaft output after subtracting the power required to run the pump was 3.22 kW, which was equivalent to 12.1% improvement in fuel consumption. About the same level of improvement in the fuel consumption was obtained over the vehicle speed range of 60 km/hr~120 km/hr.

• Journal of the Korean Solar Energy Society
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• v.25 no.4
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• pp.69-76
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• 2005

The performance of water-to-water heat pump system coupled with the ground source vertical heat exchanger is presented in this paper. The CAP program of Florida Heat Pump Co. is used to predict the heat pump performances while the EED program calculates the borehole fluid temperature. It is shown that COPH increases with decreasing the temperature of output water for the operation of heating mode and COPR increases with increasing temperature of output water for the operation of cooling mode. The value of specific heat extraction rate must be moderate to insure the reasonable installation cost of borehole system. With $1^{\circ}C$decrease of $T_{wo}$ the average COPH increase is estimated as about $0.06/^{\circ}C$(for $T_{wo}\;=\;45{\sim}60^{\circ}C$ range) while with $1^{\circ}C$ increase of $T_{wo}$ the estimation of COPR increase is about $0.13/^{\circ}C$(for $T_{wo}\;= \;5{\sim}11^{\circ}C$ range) at the specific heat extraction rate of 30W/m.

• The KSFM Journal of Fluid Machinery
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• v.18 no.1
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• pp.37-43
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• 2015

A Beta-type Stirling engine is developed and tested on the operation stability and cycle performance. The flow rate for cooling water ranges from 300 to 1500 ml/min, while the temperature of heat source changes from 300 to $500^{\circ}C$. The internal pressure, working temperatures, and operation speed are measured and the engine performance is estimated from them. In the experiment, the rise in the temperature of heat source reduces internal pressure but increases operation speed, and overall, enhances the power output. The faster coolant flow rate contributes to the high temperature limit for stable operation, the cycle efficiency due to the alleviated thermal expansion of power piston, and the heat input to the engine, respectively. The experimental Stirling engine showed the maximum power output of 12.1 W and the cycle efficiency of 3.0 % when the cooling flow is 900 ml/min and the heat source temperature is $500^{\circ}C$.

• Transactions of Materials Processing
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• v.12 no.5
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• pp.473-478
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• 2003

This study presents the enhancement of forgeability of SNCM522H materials. Target parts are output shaft(OP shaft) used as components of power train for automobiles. To carry out cold forging process of OP shaft by 1 pass instead of existing 2 pass process, studies in terms of process design and heat treatment were performed. To introduce the new process, the finite element method was accomplished, and to assess the validity of proposed heat treatment cycle, several experiments(hardness test, observation of optical microstructures, tensile test) were carried out. The 2Pass forging process could be reduced as lPass process through improvement of process and heat treatment technology and that would give cost reduction.

• Journal of the Korean Solar Energy Society
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• v.33 no.2
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• pp.70-77
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• 2013

Recently the radiant panel heating and cooling system has been regarded as an alternative of low temperature heating and high temperature cooling by applying the renewable energy sources to the heating and cooling of buildings. Especially this system can be used as HVAC system alternatives in super high-rise buildings for energy saving and thermal comfort. Also it can be possible to reduce the plenum space because the minimum ventilation air will be supplied into the space. This study focused on the evaluation the basic characteristics of thermal output in prefabricated steel wall panel system for radiant heating and cooling. In order to evaluate the thermal output according to both various supply water temperatures and supply water flow rates, three-dimensional dynamic heat transfer analysis was performed. As results, for the heating mode, thermal output increased by 26% with the supply temperature increasing by $5^{\circ}C$. The surface temperature of panels range within $1{\sim}3^{\circ}C$. For the cooling mode, thermal output decreased by 18.2% with the supply temperature increasing by $2^{\circ}C$. The surface temperature of panels range within $0.5{\sim}1^{\circ}C$ and it was shown the even temperature distribution.

• Journal of Advanced Marine Engineering and Technology
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• v.36 no.5
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• pp.595-602
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• 2012

In this study, for the purpose of reduction of $CO_2$ gas emission and to increase recovery of waste heat from ships, the ORC (Organic Rankine Cycle) is investigated and offered for the conversion of temperature heat to electricity from waste heat energy from ships. Simulation was performed with waste heat from the exhaust gasse which is relatively high temperature and cooling sea water which is relatively low temperature from ships. Various fluid is used for simulation of the ORC system with variable temperature and flow condition and efficiency of system and output power is compared. Finally, 2,400kW output power is obtained by system optimization of the preheater and reheater utilizing waste heat form sea water cooling system.

• Current Photovoltaic Research
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• v.8 no.4
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• pp.124-128
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• 2020

Output power of photovoltaic (PV) modules installed outdoors decreases every year due to environmental conditions such as temperature, humidity, and ultraviolet irradiations. In order to promote the installation of PV modules, the reliability must be guaranteed. One of the important factors affecting reliability is intermetallic compounds (IMC) layer formed in ribbon solder joint. For this reason, various studies on soldering properties between the ribbon and cell have been performed to solve the reliability deterioration caused by excessive growth of the IMC layer. However, the IMC layer of the PV module interconnected by multi-wires has been studied less than using the ribbon. It is necessary to study soldering characteristics of the multi-wire module for improvement of its reliability. In this study, we analyzed the growth of IMC layer of the PV module with multi-wire and the degradation of output power through damp-heat test. The fabricated modules were exposed to damp-heat conditions (85 ºC and 85 % relative humidity) for 1000 hours and the output powers of the modules before and after the damp-heat test were measured. Then, the process of dissolving ethylene vinyl acetate (EVA) as an encapsulant of the modules was performed to observe the IMC layer. The growth of IMC layer was evaluated using OM and FE-SEM for cross-sectional analysis and EDS for elemental mapping. Based on these results, we investigated the correlation between the IMC layer and output power of modules.

• Journal of the korean Society of Automotive Engineers
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• v.5 no.1
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• pp.89-93
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• 1983

This paper describes on experimental investigation into the heat dissipation of Diesel engine, placing emphasis on the variations of compression ratio and cooling water temperature. The engine used for this test was a vertical single-cylinder four-cycle type, having a direct injection. Engine performance and heat transfer rates was tested under the compression ratio 14.3 and 17.4. In this study, the results showed that output and transfer rates of engine decrease in accordance with the decrease of compression ratio. The effect of cooling water temperature and injection delay of fuel on the heat dissipation brings about the decrease of heat transfer rates from cylinder to cooling water.

• 한국태양에너지학회:학술대회논문집
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• 2009.11a
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• pp.104-109
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• 2009

If the Photovoltaic(PV) Module should get physical load, the PV module will be warped according to elongation of the front glass and then micro-crack will be occurred in the heat sealed Solar Cell. This micro-crack drops output of the short circuit current and the open circuit voltage of the PV Module. This is because of increase of resistance component by micro-crack. Micro-crack at specific Solar Cell in the module reduces the durability of PV Module such as less output, Hot-Spot in the PV module caused by Solar Cell output mismatch, heat generating as resistance component caused by micro-crack. In this study, among some factors which effect to the output of crystalline PV Module, we will see how the micro-crack caused by mechanical stress effects to the electrical output of PV Module.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.1000-1003
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• 1996

Nonlinear unified predictive control(UPC) algorithm was applied to the temperature control of a batch polymerization reactor for polymethylmethacrylate(PMMA). Before the polymerization reaction is initiated, the parameters of the process model are determined by the recursive least squares(RLS) method. During the reaction, nonlinearities due to generation of heat of reaction and variation of heat transfer coefficients are predicted through the nonlinear model developed. These nonlinearities are added to the process output from the linear process model. And then, the predicted process output is used to calculate the control output sequence. The performance of nonlinear control algorithm was verified by simulation and compared with that of the linear unified predictive control algorithm. In the experiment of a batch PMMA polymerization, nonlinear unified predictive control was implemented to regulate the temperature of the reactor, and the validity of the nonlinear model was verified through the experimental results. The performance of the nonlinear controller turned out to be superior to that of the linear controller for tracking abrupt changes in setpoint.