• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.14 no.4
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• pp.7-12
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• 2018

Energy performance of electric heater and geothermal source heat pump type hot air dryers are compared in this study. For set temperatures of $30^{\circ}C$, $35^{\circ}C$ and $40^{\circ}C$, radish is dried from initial mass 60 kg until it gets 5 kg, where the difference equals the amount of water removed. As set temperature is increased, drying time is shortened for both electric heater and heat pump types, however energy efficiency is decreased due to increasing electricity consumption. Moisture extraction rate(MER) of electric heater is 2.58~2.84 kg/h, and for heat pump type 2.56~2.71 kg/h, showing little difference between the two types. Specific moisture extraction rate (SMER) of electric heater is 0.94~0.96 kg/kWh, and for heat pump type 1.72~2.21 kg/kWh. SMER of heat pump type is greater by 0.78~1.25 kg/kWh than the electric heater hot air dryer, which is 1.8~2.3 times better in terms of energy efficiency.

• Transactions of the Korean Society of Automotive Engineers
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• v.10 no.1
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• pp.99-105
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• 2002

About 70% of energy input to internal combustion engine is rejected to atmosphere by heat. By utilizing this waste heat, a plenty of energy can be conserved in nationwide. One of possible ways is the thermoelectric generation to utilize engine's waste heat to provide auxiliary electric power. Under th is concept, we have been developing the thermoelectric generation system to replace the alternator by converting the waste heat in the engine's exhaust directly to electricity This system may reduce the shaft horse power of the engine, then improves the vehicle fuel economy and the exhaust emissions. In the present study, the characteristics of the electric energy and exhaust heal energy in city and highway mode driving conditions are analysed by using a gasoline passenger car. These results would be used to determine the optimum design parameters of the thermoelectric generation system.

• Advances in Automotive Engineering
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• v.1 no.1
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• pp.79-104
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• 2018

A detailed literature review is presented for the applications of the heat pump technologies on the electric vehicles Heating, Ventilation and Air Conditioning (HVAC) system. Due to legal regulations, automotive manufacturers have to produce more efficient and low carbon emission vehicles. Electric vehicles can be provided these requirements but the battery technologies and energy managements systems are still developing considering battery life and vehicle range. On the other hand, energy consumption for HVAC units has an important role on the energy management of these vehicles. Moreover, the energy requirement of HVAC processes for different environmental conditions are significantly affect the total energy consumption of these vehicles. For the heating process, the coolant of internal combustion (IC) engine can be utilized but in electric vehicles, we have not got any adequate waste heat source for this process. The heat pump technology is one of the alternative choices for the industry due to having high coefficient of performance (COP), but these systems have some disadvantages which can be improved with the other technologies. In this study, a literature review is performed considering alternative refrigerants, performance characteristics of different heat pump systems for electric vehicles and thermal management systems of electric vehicles.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.11 no.4
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• pp.22-27
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• 2015

Quality characteristics of Shiitake mushroom using two types of dryers, energy-efficient heat pump hot-air dryer and electric heater hot-air dryer were compared. Energy consumed during drying by heat pump hot-air dryer and electric heater hot-air dryer were 22.8 kWh and 28.9 kWh, respectively. Total polyphenol content of heat pump hot-air dryer and electric heater hot-air dryer after drying were $290.55{\pm}10.56ppm$ and $192.99{\pm}6.53ppm$, respectively. No differences were observed between dryers in reconstitution rate and browning ratio after drying. Also, there were no differences between dryers in color value and ${\Delta}E$ value after drying. Shiitake mushroom drying at $45^{\circ}C$ by heat pump hot-air dryer was proved to be more efficient in energy consumption than by electric heater hot-air dryer.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.11 no.4
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• pp.1-6
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• 2015

In this study, energy performance of two types of food dryers which are electric heater and heat pump is studied experimentally. With drying chamber temperatures controlled at 45, 50 and $55^{\circ}C$, sliced radish is dried from an initial mass of 90 to final 7 kg. Moisture content, drying time, total power consumption, MER (moisture extraction rate, kg/h) and SMER (specific moisture extraction rate, kg/kWh) are measured and analyzed. As the drying chamber temperature is increased, drying time is shortened but energy efficiency is reduced for both types. For an electric heater dryer, the effect of chamber temperature on drying time is significant but less significant on energy efficiency. For a heat pump dryer, the dependence of chamber temperature on drying time is weak but strong on energy efficiency. Temperature levels have little effect on electric heater dryer performance but strong effect on heat pump dryer which operates on a vapor compression refrigeration cycle. The energy performance of the heat pump dryer is superior with an average SMER of 2.175 kg/kWh which is 2.22 times greater than that of the electric heater dryer with SMER of 1.224 kg/kWh.

• KEPCO Journal on Electric Power and Energy
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• v.5 no.3
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• pp.215-222
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• 2019

This work is experimental study of 10 kW specialized Combined Ocean Thermal Energy Conversion. We propose a C-OTEC technology that directly uses exhaust thermal energy from power station condensers to heat the working fluid (R134a), and tests the feasibility of such power station by designing, manufacturing, installing, and operating a 10 kW-pilot facility. Power generation status was monitored by using exhaust thermal energy from an existing power plant located on the east coast of the Korean peninsula, heat exchange with 300 kW of heat capacity, and a turbine, which can exceed enthalpy efficiency of 45%. Output of 8.5 kW at efficiency of 3.5% was monitored when the condenser temperature and seawater temperature are $29^{\circ}C$ and $7.5^{\circ}C$, respectively. The evaluation of the impact of large-capacity C-OTEC technology on power station confirmed the increased value of the technology on existing power generating equipment by improving output value and reducing hot waste water. Through the research result, the technical possibility of C-OTEC has been confirmed, and it is being conducted at 200 kW-class to gain economic feasibility. Based on the results, authors present an empirical study result on the 200 kW C-OTEC design and review the impact on power plant.

• 한국태양에너지학회:학술대회논문집
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• 2011.11a
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• pp.333-337
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• 2011

Central control air-conditioning systems are being replaced with individually controlled air-conditioning system in the university. The amount of growth of electricity consumption is due to the increasing demand of electric heat pump. In winter and summer, the energy consumption showed a tendency to increase. On the other hand, showed less energy in spring and autumn. Increase the amount of electricity than the degree of decline in gas consumption was higher. Can be considered as transitional phenomena. Because electric heat pump, gas driven heat pump and the absorption chiller-heater are used at the same time in some of the buildings.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.30 no.4
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• pp.167-174
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• 2018

The geothermal heat pump systems were installed for heating and cooling of public buildings in Jincheon Eco-friendly Energy town. The heat pump system was operated at night to save on operational costs, and the cold heat was stored in thermal energy storage (TES). In this study, the performance of geothermal heat pump systems with the TES during the summer season was analyzed, and the operational costs with and without the TES were compared. The electric chiller model was used to simulate a heat pump applied without the TES system. Electric rates of each system were measured to calculate operational costs. When the TES is used in the air conditioning system, the electric load (30.4 MWh) calculated in the daytime can move to off-peak load time, and the operational cost is reduced by 36~54%.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.246-246
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• 2010

In this study, the effect of wast heat-electric energy conversion according to temperature difference between two sides of a thermoelectric module was investigated as a way of electric energy conversion from waste heat generated in machinery system like automobile system.

• 한국전산유체공학회:학술대회논문집
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• 2008.03b
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• pp.381-384
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• 2008

This paper presents an operational technique to maximize profit of a cogeneration power plant. To minimize errors in a loss and gain analysis of a cogeneration power plant, the energy sale profit in the cost-based-pool electric power trade market, the heat sale profit, and the supplementary fund profit for electric power industry are taken into consideration. The objective is to optimize the heat-electric power ratio to maximize profit of a cogeneration power plant. Furthermore, the constrained bidding technique to optimize heat-electric power ratiocan be obtained. Profits from of a cogeneration power plant are composed of three categories, such as the energy sale profit in the cost-based-pool electric power trade market, the heat sale profit, and the supplementary fund profit for electric power industry. Profits of a cogeneration power plant are varied enormously by the operation modes. The profits are mainly determined by the amount of constrained heat generation in each trading time. And the three profit categories arecoupled tightly via the heat-electric power ratio. The result of this case study can be used as a reference to a cogeneration power plant under the power trading system considered in this case.