• 설비공학논문집
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• 제29권1호
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• pp.38-42
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• 2017

This study proposes an idea for energy saving in apartment machine rooms. A conventional district heating system is equipped with constant-flow pumps and bypass valves to regulate pump differential pressure. Each family unit is equipped with a constant-flow on/off valve. This leads to excessive hot water circulation and a high return temperature. To reduce energy loss, this study assumes that each family unit is renovated with a heating valve which regulates the return temperature at $35^{\circ}C$. The hot water supply pump is also replaced with a pump with an inverter to vary flow rate. Expected energy savings is then estimated from field test data. According to the results, pump electricity consumption was reduced by 6,100 kWh for a family unit building over about half a year. The supply temperature can also be lowered by $5^{\circ}C$, which can contribute to a production of electricity of 10.3 kWh/ton of hot water.

• 한국태양에너지학회 논문집
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• 제26권4호
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• pp.119-126
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• 2006

This study describes thermal performance of heating and cooling demonstration system using ETSC(Evacuated tubular solar collector) installed at Seo-gu art center of Kwangju. For demonstration study, a reading room with about $350m^2$ was heated and cooled using that system. The demonstration system was consisted of ETSCs, storage tank, hot water supply tank, subsidiary boiler, and subsidiary tank. From January to March in 2006, demonstration test were performed with 4 control mode to find the optimum control condition for solar thermal system. After experiments and analysis, this study found that solar thermal system of control mode IV was corresponded to 78% for the hot water supply and 49% for space heating.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2006년도 하계학술발표대회 논문집
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• pp.832-837
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• 2006

This study describes thermal performance of heating and cooling demonstration system using ETSC(Evacuated tubular solar collector) installed at Seo-gu art center of Kwangju. For demonstration study, a reading room with about $331m^2$ was heated and cooled using that system. The demonstration system was consisted of ETSCs, storage tank, hot water supply tank, subsidiary boiler, and subsidiary tank. From January to March in 2006, demonstration test were performed with 4 control mode to find the optimum control condition for solar thermal system. After experiments and analysis, this study found that solar thermal system of control mode IV was corresponded to 78% for the hot water supply and 49% for space heating.

• 한국태양에너지학회:학술대회논문집
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• 한국태양에너지학회 2012년도 춘계학술발표대회 논문집
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• pp.451-456
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• 2012

This study was carried out to evaluate thermal performance of the renewable hybrid heat supply system with solar thermal system and wood pellet boiler for Zero Carbon Green home of apartment houses. The hybrid heat supply system was set up at Korea Institute Energy Research in 2011. The system was comprised of the wood pellet boiler unit with heat capacity designed as 20,000 kacal/hr, a evacuated tubular solar collector 3.74 $m^2$ of aperture area at the $20^{\circ}$ install angle, a 0.3 $m^3$ hot water storage tank, a 0.15 $m^3$ hot water storage tank for space heating. Thermal performance tests for one-house of apartment house were carried out by hot water load and heating load in winter season through the hybrid heat supply system. As a result, hot water energy supplied by the hybrid heat supply system was 11kWh in a day. Solar thermal energy portion was 2.99kWh which is 27% of the total hot water energy supply. wood pellet boiler supply portion was 8.017kWh which is 73% of the total hot water energy supply.

• 설비공학논문집
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• 제20권3호
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• pp.175-180
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• 2008

Flow quantity to supply to a coil in floor heating system is important to achieve comfortable indoor air condition in the winter season. The hot water header is used to distribute the water into the coil. Experimental study has been performed using the water header that have 5 branches consisted of flow control valves and automatic shut-off valves. Each branch line connected it with X-L pipe. Experimental tests accomplished it to investigate the flow distribution characteristics of the hot water header. Experimental results show that the selection of the pump head and differential pressure are very important to save running energy of the system, and high differential pressure needs more friction loss in the case of suitable differential pressure for balancing of the header.

• 한국기계기술학회지
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• 제13권1호
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• pp.113-118
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• 2011

To analyze and verify the effect of replacing thermal storage heater by a cascade cycle heat pump using midnight electricity was installed and tested at a customer's house in Wonju, Korea. The electric night storage heater is consist of 30kW electric heater and 2,700 liters of thermal storage water tank to supply hot water for warming house floor. The power for electric heater was cut off and hot water was only generated by cascade cycle heat pump. Current thermal storage water tank was not eliminated and electric heater wiring was modified. Some operation logic of the heat pump was also modified for proper operation. The required capacity of the heat pump and hot water temperature for given warming condition were estimated. The estimated capacity of heat pump was about 19kW and estimated hot water temperature for proper heating was at least $75^{\circ}C$.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1991년도 한국자동제어학술회의논문집(국내학술편); KOEX, Seoul; 22-24 Oct. 1991
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• pp.232-237
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• 1991

Digital Variable Structure Controller(DVSC) is proposed to control variable speed recirculating pump for hot-water heating control system. In this study, nonlinear sliding line is used beyond output error boundary layer and PID sliding line is used within the layer. For long dead time compensation, constraint is added to Smith predictor algorithm. Steady state error is eliminated by using the proposed sliding line in spite of heating load change. By decreasing sampling time, good sliding motion is yielded but system output noise bv flow dynamics is amplified.

• 설비공학논문집
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• 제14권12호
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• pp.1092-1101
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• 2002

The objective of this study is to develop energy saving strategies for indoor swimming pools and to estimate the effect of each energy saving strategy. For this purpose, field measurements regarding pool water heating energy, domestic hot water heating energy are conducted and a base energy consumption model is implemented using the DOE-2.1E program. The results of the study reveal that 25% of the total pool water heating energy may be saved by using night time pool covers, 27% of the total domestic hot water heating energy may be saved by using a waste water heat recovery system (effic. 60%), and of the total ventilation energy may be saved using an exhaust air heat recovery system (effic. 60%).

• Journal of Biosystems Engineering
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• 제25권3호
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• pp.221-226
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• 2000

Hot air heater with light oil burner is the most common heater for greenhouse heating in the winter season in Korea. However, since the thermal efficiency of the heater is about 80∼85%, considerable unused heat amount in the form of exhaust gas heat discharges to atmosphere. In order to capture this exhaust heat a heat recovery system for plant bed heating in the greenhouse was built and tested in the hot air heating system of greenhouse. The heat recovery system is made for plant bed or soil heating in the greenhouse. The system consisted of a heat exchanger made of copper pipes, ${\Phi}12.7{\times}0.7t$ located in the rectangular column of $330{\times}330{\times}900mm$, a water circulation pump, circulation plastic pipe and a water tank. The total heat exchanger area is 1.5$m^2$, calculated considering the heat exchange amount between flue gas and water circulated in the copper pipes. The system was attached to the exhaust gas path. The heat recovery system was designed as to even recapture the latent heat of flue gas when exposing to low temperature water in the heat exchanger. According to the performance test it could recover 45,200 to 51,000kJ/hr depending on the water circulation rates of 330 to $690\ell$/hr from the waste heat discharged. The exhaust gas temperature left the heat exchanger dropped to $100^{\circ}C$ from $270^{\circ}C$ by the heat exchange between the water and the flue gas, while water gained the difference and temperature increased to $38^{\circ}C$ from $21^{\circ}C$ at the water flow rate of $690\ell$/hr. By the feasibility test conducted in the greenhouse, the system did not encounter any difficulty in operations. And, the system could recover 220,235kJ of exhaust gas heat in a day, which is equivalent of 34% of the fuel consumption by the water boiler for plant bed heating of 0.2ha in the greenhouse.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2009년도 하계학술발표대회 논문집
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• pp.167-171
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• 2009

We conducted performance test of a 350 kW class wood pellet boiler installed at a dormitory whose total area is $1,354\;m^2$. The maximum heating capacity of the boiler is 350 kW(300,000 kcal/kg). The wood pellet boiler consists of 3 parts; boiler, hot water storage tank and wood pellet storage tank. In testing the boiler, we shut off hot water utility supply and open up floor heating water system in order to measure exact value of the heating output of the wood pellet boiler. To determine the efficiency and heating output of the wood pellet boiler, we measured mass flow rate of wood pellet, the lower heating value(LHV) of the wood pellet, mass flow rate and temperature of water for floor heating and so on. We measured the mass flow rate of fuel, wood pellet with respect to rotational speed of auger, wood pellet feeding screw. We also measured the flue gas concentration of the wood pellet boiler by using a gas analyser. The result shows that the efficiency of the wood pellet boiler is 80.6% based on lower heating value at 124 kW of heating output. At this condition, O2 concentration of the flue gas is 6.0%, CO and NOx concentrations are 85 and 102 ppm.