• 한국태양에너지학회:학술대회논문집
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• 2009.04a
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• pp.55-60
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• 2009

The purpose of the research is to develop the high performance solar chemical reactor for producing hydrogen using steam reforming reaction of methane. A specific shape chemical reactor is suggested: spiral type reactor. The reactor is installed on the dish-type solar thermal system of Inha University. The temperatures, $CH_4$ conversion rates are measured. At specific condition, $CH_4$ conversion rates of the spiral type reactor are about 92%. The spiral type reactor gives reasonably good performance without any problems caused by highly concentrated solar radiation.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.22 no.1
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• pp.40-48
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• 2010

The purpose of the research is to develop the high performance solar chemical reactor for producing hydrogen using steam reforming reaction of methane. A specific shape chemical reactor is suggested : spiral type reactor. The reactor is installed on the dish-type solar thermal system of Inha University. The temperatures, $CH_4$ conversion rates, and Hz proportion are measured. At specific condition, $CH_4$ conversion rates of the spiral type reactor are about 91%, and Hz proportion are about 66%. The spiral type reactor gives reasonably good performance without any problems caused by highly concentrated solar radiation.

• Journal of Mechanical Science and Technology
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• v.14 no.12
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• pp.1403-1411
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• 2000

Heat losses from the receivers for a dish-type solar energy collecting system constructed at Korea Institute of Energy Research are analyzed. The Stine and McDonald's model is used to estimate the convection loss. The Net Radiation method and the Monte-Carlo method are used to calculate the radiation heat transfer rate from the inside surface of the receiver to the surroundings. Two different receivers are suggested here and the performances of the receivers are estimated and compared with each other based on the prediction of the amount of heat losses from the receivers. The effects of the receiver shape and the radiation properties of the surface on the thermal performance are investigated. The performance of Receiver I is better than that of Receiver II, and the amount of solar irradiation that is not captured by the captured by the receiver after being reflected by the concentrator becomes significant if the temperature of the working fluid is low.

• Journal of the Korean Solar Energy Society
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• v.33 no.2
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• pp.93-100
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• 2013

Two-step thermochemical cycle using ferrite-oxide($Fe_2O_4$) device was investigated. The $H_2O$(g) was converted into $H_2$ in the first experiment which was performed using a dish type solar thermal system. However the experiment was lasted only for 2 cycles because the metal oxide device was sintered and broken down. Another problem was that the reaction was taken place mainly on a side of the metal oxide device. The m-$ZrO_2$, which was widely known as a material preventing sintering, was applied on the metal oxide device. The ferrite loading rate and the thickness of the metal oxide device were increased from 10.67wt% to 20wt% and from 10mm to 15mm, respectively. The chemical reactor having two inlets was designed in order to supply the reactants uniformly to the metal oxide device. The second-experiment was lasted for 5 cycles, which was for 6 hours. The total amount of the $H_2$ production was 861.30ml. And cerium oxide($CeO_2$) device was used for increasing $H_2$ production rate. $CeO_2$ device had low thermal resistance, however, more $H_2$ production rate than $Fe_2O_4$ device.

• Journal of the Korean Solar Energy Society
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• v.31 no.1
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• pp.107-114
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• 2011

Two-step thermochemical cycle using ferrite-oxide($Fe_3O_4$) device was investigated. The $H_2O$(g) was converted into $H_2$ in the first experiment which was performed using a dish type solar thermal system. However the experiment was lasted only for 2 cycles because the metal oxide device was sintered and broken down. Another problem was that the reaction was taken place mainly on a side of the metal oxide device. The $m-ZrO_2$, which was widely known as a material preventing sintering, was applied on the metal oxide device. The ferrite loading rate and the thickness of the metal oxide device were increased from 10.67wt% to 20wt% and from 10mm to 15mm, respectively. The chemical reactor having two inlets was designed in order to supply the reactants uniformly to the metal oxide device. The second-experiment was lasted for 5 cycles, which was for 6 hours. The total amount of the $H_2$ production was 861.30mL.

• Journal of the Korean Solar Energy Society
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• v.34 no.6
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• pp.11-18
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• 2014

Two-step water splitting thermochemical cycle with $CeO_2$ foam device was investigated by using a solar simulator composed of 2.5 kW Xe-Arc lamp and mirror reflector. The hydrogen production of $CeO_2$ foam device depending on reaction temperature of Thermal-Reduction step and Water-Decomposition step was analyzed, and the hydrogen production of $CeO_2$ and $NiFe_2O_4/ZrO_2$ foam devices was compared. As a result, the amount of reduced $CeO_2$ considerably varies according to the reaction temperature of Thermal-Reduction step. and hydrogen production was not much when the amount of reduced $CeO_2$ decreased even if the reaction temperature of Water-Decomposition step was high. Therefore, it is very important to keep the reaction temperature of Thermal-Reduction step high in two-step thermochemical cycle with $CeO_2$.

• Journal of the Korean Solar Energy Society
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• v.37 no.5
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• pp.27-37
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• 2017

In this study, an artificial solar simulator composed of a 2.5 kW Xe-Arc lamp and mirror reflector was used to carry out the solar thermal two step thermochemical water decomposition cycle which can produce high efficiency continuous hydrogen production. Through various operating conditions, the change of hydrogen production due to the possibility of a dual-zone reactor and heat recovery were experimentally analyzed. Based on the reaction temperature of Thermal-Reduction step and Water-Decomposition step at $1,400^{\circ}C$ and $1,000^{\circ}C$ respectively, the hydrogen production decreased by 23.2% under the power off condition, and as a result of experiments using heat recovery technology, the hydrogen production increased by 33.8%. Therefore, when a thermochemical two-step water decomposition cycle is conducted using a dual-zone reactor with heat recovery, it is expected that the cycle can be operated twice over a certain period of time and the hydrogen production amount is increased by at least 53.5% compared to a single reactor.

• Journal of the Korean Solar Energy Society
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• v.37 no.2
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• pp.13-22
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• 2017

Two-step water splitting thermochemical cycle with $CeO_2/ZrO_2$ foam device was investigated by using a solar simulator composed of 2.5 kW Xe-Arc lamp and mirror reflector. The hydrogen production of $CeO_2/ZrO_2$ foam device depending on heat recovery of Thermal-Reduction step and Water-Decomposition step was analyzed, and the hydrogen production of $CeO_2/ZrO_2$ and $NiFe_2O_4/ZrO_2$ foam devices was compared. Resultantly, the quantity of hydrogen generation increased by 52.02% when the carrier gas of Thermal-Reduction step is preheated to $200^{\circ}C$ and, when the $N_2/steam$ is preheated to $200^{\circ}C$ in the Water-Decomposition step, the quantity of hydrogen generation increased by 35.85%. Therefore, it is important to retrieve the heat from the highly heated gases discharged from each of the reaction spaces in order to increase the reaction temperature of each of the stages and thereby increasing the quantity of hydrogen generated through this.

• Journal of the Korean Solar Energy Society
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• v.33 no.3
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• pp.42-50
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• 2013

Solar thermal reactor was studied for hydrogen production with a two step thermochemical cycle including T-R(Thermal Reduction) step and W-D(Water Decomposition) step. NiFe2O4 and Fe3O4 supported by monoclinic ZrO2 were used as a catalyst device and Ni powder was used for decreasing the T-R step reaction temperature. Maintaining a temperature level of about $1100^{\circ}C$ and $1400^{\circ}C$, for 2-step thermochemical reaction, is important for obtaining maximum performance of hydrogen production. The controller was designed for adjusting high temperature solar thermal energy heating the foam-device coated with nickel- ferrite powder. A Pill temperature control system was designed based on 2-step thermochemical reaction experiment data(measured concentrated solar radiation and the temperature of foam device during experiment). The cycle repeated 5 times, ferrite conversion rate are 4.49~29.97% and hydrogen production rate is 0.19~1.54mmol/g-ferrite. A temperature controller was designed for increasing the number of reaction cycles related with the amount of produced hydrogen.

• 한국신재생에너지학회:학술대회논문집
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• 2008.05a
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• pp.169-173
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• 2008

Stirling engine is a promising heat engine with a high efficiency, muti-fuel capability, low emission, quiet operation, very low maintenance and long life. As one of the promising applications, solar power system based on the Stirling dish, providing net solar-to-electric conversion efficiencies reaching 30%, can operate as stand-alone units in remote locations or can be linked together in groups to provide utility-scale power. This paper introduced a new Scroll-type Stirling engine, being developed for solar power, superior to conventional Stirling engines. The Scroll-type Stirling engine is characterized as traits of continuous and wholly separated compression and expansion; one-way flow system; direct cooling and heating the fluid in the working spaces through the extensive inner surfaces of scroll wraps. All theses traits contribute to achieving thermodynamic cycle closer to the ideal Stirling cycle (exactly speaking, Ericsson cycle).