• Proceedings of the KSME Conference
• /
• 2001.06e
• /
• pp.668-671
• /
• 2001

For the saving of energy consumption, it is necessary that the high efficient energy transfer machine. We found the optimum operating condition of screw water chiller during this performance test. The specifications of compressor for this performance test are as follows. Built-in volume ratio; Vi=2.4, using refrigerant; HCFC-22, nominal motor output; 60kW(80Hp). We found the test results on water cooled chiller standard test condition that the evaporating capacity is increased 8% maximum and 5.6% under same operating condition. and COP is increased 11 % max. and 8% under same operating condition with change of the evaporating inlet/outlet condition. For the results of these test, we can estimate the optimum operating condition of water cooled type screw chiller.

• The KSFM Journal of Fluid Machinery
• /
• v.3 no.4 s.9
• /
• pp.44-51
• /
• 2000

The present study has been conducted to design the high efficiency centrifugal compressor for a R134a turbo-chiller. The centrifugal compressor consists of an impeller with splitters, two vaneless diffusers, a low-solidity vaned diffuser and a volute. A cycle analysis program for a turbo-chiller was developed to obtain compressor design parameters and requirements. We have designed the high efficiency centrifugal compressor by applying the repeated design procedure including a meanline design, a 3D geometry generation and fluid dynamic loading calculations.

• Journal of Advanced Marine Engineering and Technology
• /
• v.28 no.2
• /
• pp.243-251
• /
• 2004

Absorption chiller/heater can utilize the unused energy of the daily life waste heat, the industry waste heat. the solar energy and the earth energy. These can contribute to energy savings. But the absorption chiller/heater has a demerit that the size of absorption chiller/heater is larger than that of the vapor compression type based on same capacity. In this study. the experimental apparatus of an absorber is manufactured as a plate. which is newly applied in an absorber. The experimental apparatus is composed of a plate type absorber. which can increase the heat exchange area per unit volume and thus facilitating to deeply investigate more detail features instead of that done by the existing type. i.e.. horizontal tube bundle type. The characteristics of heat transfer and refrigeration capacity are studied experimentally. The absorption enhancement by using surfactant is closely examined through the experiment and comparative figures are presented in quantitative and qualitative analysis.

• Journal of KSNVE
• /
• v.10 no.6
• /
• pp.963-970
• /
• 2000

The turbo chiller uses centrifugal compressor, which operates at about 14,500 rpm. Due to the high rpm of the impeller, the noise of chiller males one of the serious problems. The possibility of the sound reduction by using absorbing material is studied in this paper. The generated sound propagates through the duct and then radiates to the outer field. So, the use of sound absorption material inside the duct is one of the effective methods. To study the effect of location of the material, we use Boundary Element Method to analyze the sound field inside the duct system. Numerical study shows the highest sound pressure region is near the elbow of curved duct. From the numerical study, it is also shown that appropriate use of sound absorbing material at this region makes 8dB reduction of the highest noise level.

• Proceedings of the SAREK Conference
• /
• 2008.06a
• /
• pp.36-41
• /
• 2008

Fault detection and diagnosis(FDD) system is beneficial in equipment management by providing the operator with tools which can help find out a failure of the system. An experimental study has been performed on fault detection and diagnosis method for a water chiller. Bayes classifier, which is one of classical pattern classifiers, is adopted in deciding whether fault occurred or not. FDD algorithm can detect refrigerant leak failure, when 20% amount of charged refrigerant for normal operation leaks from the water chiller. The refrigerant leak failure caused COP reduction by 6.7% compared with normal operation performance. When two kinds of faults, such as a decrease in the mass flow rate of cooling water and temperature sensor fault of cooling water inlet, are detected, COP is a little decreased by these faults.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.11 no.3
• /
• pp.401-413
• /
• 1999

An ice storage cooling facility with cooling capacity of 150㎾ has been constructed for the purpose of developing optimal design and control strategy for an ice storage system. As the first step to this purpose, a computer program has been developed to simulate the operation of the ice storage system and examined precisely by comparing the results with those measured from the test facility. With the simulation program verified from the comparison, a design procedure has been developed to determine the minimum capacity required for each operation strategy available commercially. It is shown that the minimum sizes of the chiller and the storage tank are strongly dependent on the control strategy, i.e., chiller priority or storage priority, but less affected by the arrangement method, i.e., chiller upstream or chiller downstream.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.8 no.3
• /
• pp.351-360
• /
• 1996

This study focuses on the development and evaluation of the high efficiency absorption chiller-heater, which can be applied to a direct gas fired, double effect system with 40RT (508,000kJ) cooling capacity. The performance of the absorption chiller-heater is investigated through cycle simulation and experiment to obtain the system characteristics with the inlet tenperature of cooling, chilled water, and gas input flow rate. The efficiency of the different cycles has been studied and the simulation and experiment results show that higher coefficient of performance could be obtained for mixed flow cycle. The five percent difference was obtained from the comparison between experimental and cycle simulation results. As a result of this study, the optimum designs were determined based on the operating conditions and the coefficient of performance.

• International Journal of Air-Conditioning and Refrigeration
• /
• v.13 no.1
• /
• pp.1-10
• /
• 2005

Screw compressor chillers are widely used in refrigeration for capacity over 30 RT. In general, chillers operate under part-load conditions during most of the time. Therefore, information on the characteristics of part-load is very important for better chiller performance and energy economy. In this study, performance tests of screw chiller with economizer using R22 and R407C under part-load conditions have been performed for various secondary fluid temperatures. Adoption of an economizer system increased the cooling capacity and improved COP except for lower part-load condition when economizer volume ratio is 1.01. For the same cooling capacity condition at part-load, COP's of both non-economizer and economizer system showed similar values.

• Journal of Advanced Marine Engineering and Technology
• /
• v.24 no.4
• /
• pp.478-485
• /
• 2000

An experimental study of the absorption process of water vapor into lithium bromide solution was performed. For the purpose of development of high performance absorption chiller-heater utilizing Lithium Bromide solution as working fluid, the absorber is the most effective to improve the performance of an absorber because it requires the largest heat transfer area in an absorption chiller-heater system. This paper introduces bare tube and inner ribbed notched fin tube for the absorber of absorption chiller-heaters. Inner ribbed notched fin tube has about 10∼20% higher heat and mass transfer performance than bare tube conventionally used in absorbers and the it is expected to perform high heat and mass transfer. This paper will provide important information on the selection of absorber tubes in commercial absorption chill-heaters.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.11 no.5
• /
• pp.570-578
• /
• 1999

An experimental study has been performed on heat and mass transfer in a falling film absorber with a strong lithium bromide solution in small-sized household absorption chiller/heater. Components were concentrically arranged in a cylindrical form. from the center, low temperature generator, absorber and evaporator. This arrangement of helical-typed heat exchangers allows to make the machine much more compact than conventional one. Experimental measurements were conducted with a helical absorber and the obtained data were compared with data in the literatures. The comparison revealed that the helical absorber tube provides a similar performance to existing tube bundle absorber in heat and mass transfer. As a result, the heat and mass transfer characteristics of helical type absorber showed the possibility of the reduction in size and weight of small] capacity absorption chiller/heater.