• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.2
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• pp.145-151
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• 2010

In this study, an absorption power cycle, which can be used for a low-temperature heat source driven power cycle such as geothermal power generation, was investigated and optimized in terms of power by the simulation method. A steady-state simulation model was adopted to analyze and optimize its performance. Simulations were carried out for the given heat source and sink inlet temperatures, and the given flow rates were based on the typical power plant thermal-capacitance-rate ratio. The cycle performance was evaluated for two independent variables: the ammonia fraction at the separator inlet and the maximum cycle pressure. Results showed that the absorption power cycle can generate electricity up to about 14 kW per 1 kg/s of heat source when the heat source temperature, heat sink temperature, and thermal-capacitance-rate ratio are $100^{\circ}C$, $20^{\circ}C$, and 5, respectively.

• Journal of applied mathematics & informatics
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• v.42 no.3
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• pp.607-623
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• 2024

This article studies the effects of heat generation/absorption and thermal radiation on the unsteady magnetohydrodynamic (MHD) Casson fluid flow past a vertical plate through rotating porous medium with constant temperature and mass diffusion. It is assumed that the plate temperature and concentration level are raised uniformly. For finding the exact solution, a set of non-dimensional partial differential equations is solved analytically using the Laplace transform technique. The influence of various non-dimensional parameters on the velocity are discussed, including the effects of the magnetic parameter M, heat generation/absorption Q, thermal radiation parameter R, Prandtl number Pr, Schmidt number Sc, permeability of porous medium parameter, Casson fluid parameter γ, on velocity, temperature, and concentration profiles, which are discussed through several figures. It is found that velocity, temperature, and concentration profiles in the case of heat generation parameter Q, Casson fluid parameter γ, thermal Grashof number Gr, mass Grashof number Gc, Permeability Porous medium parameter K, and time t have retarding effects. It is also seen that the magnetic field M, Thermal Radiation parameter R, Prandtl field Pr, Schmidt number Sc have reverse effects on it.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.13 no.5
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• pp.422-430
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• 2001

In the present study, an evaporative generation process of ammonia-water solution film on the vertical plate was analysed. For the utilization of waste heat, hot water of low temperature was used as the heat source. The continuity, momentum, energy and diffusion equations for the solution film and vapor mixture were formulated in integral forms and solved numerically. Counter-current solution-vapor flow resulted in the refrigerant vapor of the higher ammonia concentration than that of co-current flow. Eve the rectification of refrigerant vapor was observed near the inlet of solution film in counter-current flow. For the optimum operation of generator using hot water, numerical experiments, based on the heat exchange and generation efficiencies. revealed the inter-relationships among the Reynolds number of the solution film and hot water, and the length of generator. Enhancement of heat and mass transport in the solution film was found to be very effective for the improvement of generation performance, especially at high solution flow rate.

• Advances in nano research
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• v.10 no.3
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• pp.221-234
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• 2021

During the previous few years, phenomenon of bioconvection along with the use of nanoparticles showed large number of applications in technological and industrial field. This paper analyzed the bioconvection phenomenon in magnetohydrodynamic boundary layer flow of a Powell-Eyring nanoliquid past a stretchable cylinder with Cattaneo-Christov heat flux. In addition, the impacts of chemical reaction and heat generation/absorption parameter are considered. By the use of appropriate transformation, the governing PDEs (nonlinear) have been transformed and formulated into nonlinear ODEs. The resulting nonlinear ODEs subjected to relevant boundary conditions are solved analytically through homotopy analysis method which is programmed in Mathematica software. Graphical and numerical results versus physical quantities like velocity, temperature, concentration and motile microorganism are investigated under the impact of physical parameters. It is noted that velocity profile enhances as the curvature parameter A and Eyring-Powell fluid parameter M increases but a decline manner for large values of buoyancy ratio parameter Nr and bio-convection Rayleigh number Rb. In the presence of Prandtl number Pr, Eyring-Powell fluid parameter M and heat absorption parameter ��, temperature profile decreases. Nano particle concentration profile increases for increasing values of magnetic parameter Ha and thermophoresis parameter Nt. The motile density profile has revealed a decrement pattern for higher values of bio-convection Lewis number Lb and bio-convection peclet number Pe. This study may find uses in bio-nano coolant systems, advance nanomechanical bio-convection energy conversion equipment's, etc.

• Advances in nano research
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• v.14 no.3
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• pp.295-302
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• 2023

The characteristics of motile microorganism and three dimensional Darcy-Forchheimer nanofluid flow by a porous rotatable disk with heat generation/absorption is reported. Thermophoretic and Brownian motion aspects are included by utilizing Buongiorno model. Moreover, slip conditions are considered on velocity, thermal, concentration and microorganism. Shooting procedure is implemented to find the numerical results of physical quantities are evaluated parametrically. The different physical parameters like heat sink/source parameter, thermal, Brownian number, thermophoresis parameter, concentration, Peclet number, bioconvected Lewis number, microorganism on concentration and density of motile microorganism distributions is considered. Graphs of concentration and microorganism are plotted to examine the influence of distinct prominent flow parameters.

• 한국신재생에너지학회:학술대회논문집
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• 2008.05a
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• pp.638-641
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• 2008

Geothermal water at moderate temperature in a range between 30 to $50^{\circ}C$ exists sparse in surroundings. Mostly they are utilized as heat or water source at spar zones in Korea. However, a large portion of used water is discarded due to its poor recovery quality and inferior application technologies. In this research, an innovative heat pump system based on the hybrid concept that combinate compression cycle and absorption cycle was investigated mathematically. The hybrid heat pump aims to recycle various kind of the heat sources at moderate temperature including geothermal water effectively. The prime objective of the simulation is to design a compression/absorption hybrid heat pump system which can make high temperature above the level of $90^{\circ}C$ and low temperature of $20^{\circ}C$ as well at the same using $50^{\circ}C$ geothermal heat water. As a result, primitive data was provided as a basis to design a prototype 3 RT class hybrid heat pump.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.16 no.9 s.114
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• pp.964-970
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• 2006

Micro gas turbine(MGT) has received attention recently as small-scale distributed power sources. With characteristics such as their small size, lightweight, low maintenance cost and minimal vibrations during operation, they are expected to become widespread in a wide range of ' applications, including residential and small-scale industrial use. It is very easier to start-up and stop the MGT system which is the friendly environmental power system has just below the 9ppm NOx emmission and good quality of noise level. The exhaust heat emitted by the MGT is in the form of about $300^{\circ}C$ clean exhaust gas. The exhaust gas is suitable for absorption chiller/heater system. 1 has researched performance characteristics of the 60 kW class MGT-absorption chiller-heater system in the local condition. Variations of heat recovery from exhaust gas has measured according to micro gas turbine output of 15, 30, 45, 60kW. From those results, the performance of the MGT-absorption chiller/heater system has been evaluated.

• Solar Energy
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• v.9 no.3
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• pp.73-80
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• 1989

This paper presents as assessment based on steady-state thermodynamic analysis and computer modeling of a double effect generation absorption heating cycle for solar air-conditioning to find operating temperature ranges. The influences of component temperatures on the heating coefficients of performance and mass flow ratio have been investigated to obtain optimum operating conditions for the proposed air conditioning system. And the single and double effect absorption cycles are compared with each other over the same range of temperatures.

• Proceedings of the SAREK Conference
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• 2008.06a
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• pp.1249-1254
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• 2008

Industrial low temperature waste heat exists sparse in surroundings but its amount is huge. However, large portion of waste heat is discarded due to its poor recovery quality and inferior application technologies. The heat pump system in this research is based on the hybrid combination of compression cycle and absorption cycle in order to recycle various kind of industrial waste heat effectively. The prime objective is to design a compression absorption hybrid heat pump system which can produce high temperature above the level of $90^{\circ}C$ and low temperature of $20^{\circ}C$ at the same time using waste heat water of $50^{\circ}C$. A mathematical simulation was carried out as a basis to design a prototype 3 RT class hybrid heat pump. From the simulation results, fundamental parameters to design the system were obtained.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2008.10a
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• pp.235-240
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• 2008

The recent development of efficient thermal prime movers for distributed generation id changing the focus of the production of electricity from large centralized power plants to local generation units scattered over the territory. The scientific communality is addressing the analysis and planning of the distributed energy resources(der) with wide spread approaches, taking into account technical, environmental, economical and social issues. The coupling of cogeneration system to absorption/electric chillers or heat pumps as well as the interactions with renewable sources, allow for setting up multi-generation systems for building cooling heating and power(BCHP) systems of different energy vectors such as electricity, heat(at different enthalpy levels), cooling power, hydrogen, various chemical substances and so forth. Adoption of the composite multi-generation systems may lead to significant benefits in term of higher efficiency, reduced $CO_2$ emissions and enhanced economy. This paper outlines the main aspects of the BCHP system framework, illistrating its characteristics and summarizing the relevant distributed multi-generation structures.