• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.12 no.2
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• pp.1-6
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• 2016

A ground air heat exchanger (GAHX), also called earth air heat exchanger is a useful technology to be integrated with other renewable energy technologies. In this study, ground-air heat exchanger system for the air source heat pump is introduced. The purpose of this study is to design the volumetric flow rate and the length of GAHX system. A GAHX length model equation has been developed and used for calculation. GAHX thermal efficiency are recommended as 75% and 85% in order to optimize pipe length. $2,750m^3/h$, $2,420m^3/h$ of volumetric flow rate on 88.3m, 111.7m length are suggested for providing 7.5kW thermal capacity. And the number of path is recommended more than two to minimize pressure drop. For future study, advanced model equation study with ground thermal behavior and a more efficient GAHX design will be considered.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.7 no.6
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• pp.42-48
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• 1998

This paper is concerned with the heat flux distribution and energy partition for creep-feed grinding. From measurements of transient grinding temperatures in the workpiece sub-surface using an embedded thermocouple, the overall energy partition to the workpiece was estimated from moving heat source theory for a triangular heat flux distribution as 3.0% for down grinding and 4.5% for up grinding. The higher energy partition for up grinding can be attribute to the need to satisfy thermal compatibility at the grinding zone. The influence of cooling outside the grinding zone can be analytically taken into account by specifying convective heat transfer coefficients on the workpiece surface ha ahead of the heat source (grinding zone) and hb behind the heat source. The smaller energy partition together with slightly lower grinding power favors down grinding over up grinding.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2000.11c
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• pp.647-653
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• 2000

In this research the heat regenerative technology was employed to eliminate frosting on evaporator coil and improve COP of the heat pump system. This heat regenerative device(HRD) has very simple structure consisting a geared motor and a porous fiber belt passing through alternatively between cold and warm air duct. The laboratory test showed that the heat pump system with HRD yielded an impressive COP higher than 3.5 at the outside air temperature of $-7^{circ}C$ in heating mode.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.13 no.4
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• pp.1-7
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• 2017

The energy slab is a ground coupled heat exchanger equipped in building slab structures, which represents a layout similar to the horizontal ground heat exchanger (GHEX). The energy slab is installed as one component of the floor slab layers in order to utilize the underground structure as a hybrid energy structure. However, as the energy slab is horizontally arranged, its thermal performance is inevitably less than the conventional vertical GHEXs. Therefore, stainless steel (STS) pipes are alternatively considered as a heat exchanger instead of high density polyethylene (HDPE) pipes in order to enhance thermal performance of GHEXs. Moreover, not only a floor slab but also a wall slab can be utilized as a heat-exchangeable energy slab in order to maximize the use of underground space effectively. In this paper, four field-scale energy slabs were constructed in a test bed, which consist of the STS and HDPE pipe, and a series of thermal response tests (TRTs) was conducted to evaluate relative heat exchange efficiency per unit pipe length according to the pipe material and the configuration of energy slabs. The energy slab equipped with the STS pipe shows higher thermal performance than the energy slab with the HDPE pipe. In addition, thermal performance of the wall-type energy slab is almost equivalent to the floor-type energy slab.

• Journal of Energy Engineering
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• v.28 no.4
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• pp.13-18
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• 2019

The high energy penalty in amine-based post-combustion CO₂ capture process is hampering its industrial scale application. An advanced process is designed by intensive heat integration within the conventional process to reduce the stripper duty. The study presents the technical feasibility for stripper duty reduction by intensive heat integration in CO₂ capture process. A rigorous rate-based model has been used in Aspen Plus® to simulate conventional and advanced process for a 300 MW coal-based power plant. Several design and operational parameters like split ratio, stripper inter-heater location and flowrate were studied to find the optimum values. The results show that advanced configuration with heat integration can reduces the stripper heat by 14%.

• Journal of the Korean Geosynthetics Society
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• v.12 no.4
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• pp.143-147
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• 2013

Geothermal energy is easy to take advantage of renewable energy stored in the earth and the heat exchanger can be collected through a heat exchange piping system. In this study, have been developed a heat exchange pipe loop system which it could be installed in tunnel segmental linings to collect geothermal energy around the tunnel. The heat exchange pipe loop system incorporated in the tunnel segments circulate fluid to transport with heat from the surrounding ground and the heat can be used for heating and cooling of nearby structures or districts. The segmental lining incorporating heat exchange pipe loop system are called as ELS (Energy Lining Segment). There are a number of examples incorporating a heat exchange pipe loop system in a tunnel lining in Europe. In this study, a field case using Energy Lining Segment in Germany and applications in urban area are thoroughly examined. In addition, a CFD (Computational Fluid Dynamics) analysis was carried out to investigate heat flow in Energy Lining Segment.

• Proceedings of the SAREK Conference
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• 2008.06a
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• pp.1273-1278
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• 2008

A sea water source cascade heat pump was designed and tested in this study. The system was designed to perform a single stage operation in summer, as well as a cascade operation in winter to ensure the high temperature lift. A steady-state simulation model was developed to analyze and optimize its performance. The simulation results show that the R717 exhibits best performance among combinations considered in this study. A R410A also exhibits the highest performance among HFCs with the smallest compressor displacement. A 15-RT R410A-R134a pilot system was installed in the 5-story commercial building at Samcheok City by the East Sea. A scroll type R410A compressor, a reciprocating type R134a compressor, plate type condenser/ evaporator/ cascade heat exchanger and two electronic expansion valves were used to build a pilot. A titanium plate type heat exchanger is also used for the heat exchanging with a sea water. The heat source/sink water is supplied from the well below the seashore in the depth of 5 m. In the initial test of the system, supply water temperature was rising up to $67^{\circ}C$ using a sea water heat source of $9^{\circ}C$, while an ambient temperature was $4.5^{\circ}C$.

• Nuclear Engineering and Technology
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• v.34 no.4
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• pp.269-285
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• 2002

Water heat transfer experiments were carried out in a uniformly heated annulus with a wide range of pressure conditions. The local heat transfer coefficients for saturated water (low boiling have been measured just before the occurrence of the critical heat flux (CHF) along the length of the heated section. The trends of the measured heat transfer coefficients were quite different from the conventional understanding for the heat transfer of saturated flow boiling. This discrepancy was explained from the nucleate boiling in the liquid film of annular flow under high heat flux conditions. The well-known correlations were compared with the measured heat transfer coefficients. The Shah and Kandlikar correlations gave better prediction than the Chen correlation. However, the modified Chen correlation proposed in the present work showed the best agreement with the present data among correlations examined .

• Journal of the Korean Society of Industry Convergence
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• v.12 no.3
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• pp.157-162
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• 2009

Significant air temperature increases in urban areas are known as the heat island phenomenon in a global scale. Therefore, we use numerical model in order to analyze quantitative effects by using new & renewable energy on the heat island phenomenon in urban area. The present study quantitatively analyzes the Urban Heat Island Effects, Energy-Saving Effects, and Environmental Load Decrease Effect along New and Renewable Energy Application which is 10% of the Building Energy Consumption.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.27 no.3
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• pp.146-151
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• 2015

The heat transfer performance of heating medium oil fluidized bed heat exchanger was measured. The operation variables were air flow rate, air inlet temperature, moisture content, water flow rate and water inlet temperature. The outside heat transfer coefficient was determined from the heat exchanger experiment and its experimental correlation was determined as a function of air velocity and viscosity of heating medium oil. Effect of viscosity was well agreed with the previous studies. Errors of the correlation equation was less than about 10% for outside heat transfer coefficient developed in this study when compared with the measured value. Hot water with the temperature greater than $77^{\circ}C$ could be produced by using the heating medium oil fluidized bed heat exchanger.