• 한국초전도ㆍ저온공학회논문지
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• 제3권2호
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• pp.62-68
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• 2001

This paper presents manufacturing process and test results in the optimum pressure and operating frequency for the free piston free displacer(FPFD) Stirling cryocooler designed and manufactured by Korea Institute of Machinery &Materials (KIMM). FPFD Stirling cryocooler is currently under development uses opposed linear motors to drive opposed pistons . The performance of FPFD Stirling cryocooler is evaluated as a function fo charging pressure and operating frequency. In general as the operating frequency of the compressor is increaed but natural frequency of the displacer is almost constant. The prototype has achieved no load temperature of 49K and cooling capacity of 0.5W at 7.2K.

• 연구논문집
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• 통권29호
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• pp.17-27
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• 1999

The experimental results of the 17K inertance tube pulse tube cryocooler for cooling cryosensors are presented in this paper. In prototype experiments, linear compressor is driven by linear motor, and inertance tubes are inserted between one liter reservoir and pulse tube. Design of the inertance tube pulse tube cryo-cooler is conducted by ARCOPTR program of NASA Ames Research Center. To find optimal conditions of inertance tube pulse tube cryocooler, no load temperature and refrigeration capacity according to the variations of inertance tube volume, reservoir volume and charging pressure are measured. and the cool down and load characteristics at the particular conditions are presented. As the representative results, no load temperature of the cold end is 52.7K and refrigeration capacity is 5W at 72K..

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 춘계학술대회
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• pp.1709-1716
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• 2003

Stirling engine is a heat engine with a high potential efficiency, multi-fuel capability, its low emission, quiet operation, very low maintenance requirement and long life. The Stirling cycle can ideally achieve optimum thermodynamic efficiency of the Carnot cycle. But the actual efficiency of practical reciprocating Stirling engine is much less than that of ideal Stirling cycle due to several mechanical limits. This paper presents a new-type Stirling engine employing the scroll mechanism superior to the reciprocating Stirling engine. The new-type Stirling engine is characterized as traits of continuous and wholly seperated compression and expansion, one-way flow, direct cooling and heating through the extensive surfaces of scroll wraps. By means of this traits, the new-type Stirling engine can achieve thermodynamic cycle closer to the ideal Stirling cycle and have many mechanical merits. Also, the new-type Stirling cycle can be applied as Stirling refrigerator and Duplex Stirling machine.

• Journal of Mechanical Science and Technology
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• 제17권12호
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• pp.2087-2098
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• 2003

The development of numerical mathematical model to calculate both the static and dynamic characteristics of a multi-shaft gas turbine consisting of a single combustion chamber, including advanced cycle components such as intercooler and regenerator is presented in this paper. The numerical mathematical model is based on the simplified assumptions that quasi-static characteristic of turbo-machine and injector is used, total pressure loss and heat transfer relation for static calculation neglecting fuel transport time delay can be employed. The supercharger power has a cubical relation to its rotating velocity. The accuracy of each calculation is confirmed by monitoring mass and energy balances with comparative calculations for different time steps of integration. The features of the studied gas turbine scheme are the starting device with compressed air volumes and injector's supercharging the air directly ahead of the combustion chamber.

• 설비공학논문집
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• 제6권3호
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• pp.282-290
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• 1994

A numerical model for the analysis and design of orifice pulse tube refrigerators has been developed. Heat transfer coefficient and friction factors in the model vary with time, and the real physical properties such as thermal conductivity and viscosity were used to improve the accuracy of the model. Thermodynamic behavior of the working fluid within pulse tube refrigerators was investigated and the effect of design parameters, such as reservoir volume, orifice diameter, and NTU of regenerator, on the cooling load and COP was shown.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2005년도 연구개발 발표회 논문집
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• pp.467-472
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• 2005

Characteristics of a Modified regenerative cycle gas turbine has been investigated. In the cycle, the turbine expansion is divided into two parts and the regenerator locates between them. Two types of mechanical design are assumed: two-shaft and single-shaft. In particular, optimal pressure ratio division between the high and low pressure turbines is evaluated for the single shaft configuration. The part load analyses have been carried out with the aid of off-design models. In addition to the general fuel only control, a variable speed control is assumed as the part load operating strategy of the single shaft configuration. Obvious advantage with the alternative cycle is observed in the variable speed operation of the single shaft design.

• 한국초전도저온공학회:학술대회논문집
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• 한국초전도저온공학회 2003년도 학술대회 논문집
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• pp.28-32
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• 2003

Miniature inertance pulse tube refrigerator was designed and fabricated to provide optimal performance with 10W compressor. An adiabatic model was used to design an inertance pulse tube refrigerator. Among the various design parameters which should be optimized, pulse tube length and inertance tube length were considered. PdV work and various losses were calculated for various pulse tube and inertance tube length. Experiments were carried out for different pulse tube length and inertance tube length. It was shown that the experimental results were similar to the calculated results. The reason why the quantitative optimal point exists is explained.

• 한국초전도저온공학회:학술대회논문집
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• 한국초전도저온공학회 2003년도 학술대회 논문집
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• pp.33-35
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• 2003

There are three types that geometrical arrangement of the pulse tube and regenerator - in line type, U type, and coaxial type. The most compact and convenient one practical applications is the coaxial type. It can replace Stirling cryocooler without any change to the Dewar or the connection to the cooled devices. To investigate effects of the inertance tube, we perform experiments with varying inertance tube inner diameter and length. The experimental results show that optimum inertance tube inner diameter and length are 1.3mm, 1900mm respectively.

• International Journal of Air-Conditioning and Refrigeration
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• 제6권
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• pp.80-92
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• 1998

A third-order simulation model of a Vuilleumier{VM) heat pump has been developed. This model takes into account the major losses such as the heat conduction losses through regenerators and displacers, the pumping losses and the wall-to-gas heat transfer losses in active volumes, in addition to the heat exchanger and regenerator losses. The working volume was divided into 12 control volumes and the conservation equations of mass and energy were applied to each control volume. Pressure drops were considered in regenerators only. Thermodynamic behavior of the working gas in a VM heat pump was investigated and effects of the major losses and operating conditions on the performance of a VM heat pump were shown.

• 설비공학논문집
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• 제7권3호
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• pp.501-511
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• 1995

A numerical model for predicting the performance of gas distrubutor type double inlet pulse tube refrigerators has been developed. The model was based on adiabatic analysis and the losses of heat exchangers and regenerator were considered. Thermodynamic behavior of working fluid within a double inlet pulse tube refrigerator was investigated and the effects of design parameters, such as valve and orifice openings, cold heat exchanger temperature, frequency and pulse tube length, on the cooling capacity and COP were shown.