Showing papers on "Heat capacity rate published in 2011"
TL;DR: In this article, heat pipe effectiveness is defined and used to quantify the relative performance of heat pipe-assisted and fin-assisted configurations to situations involving neither heat pipes nor fins, while the fins are not as effective.
191 citations
TL;DR: In this article, a mathematical model for the overall thermal efficiency of the solar-powered high temperature differential dish-Stirling engine with finite-rate heat transfer, regenerative heat losses, conductive thermal bridging losses and finite regeneration processes time is developed.
167 citations
TL;DR: In this article, the application of nanofluids as the working fluid on a heat pipe liquid-block combined with thermoelectric cooling is investigated, and the results obtained from this technique are compared to those from other conventional cooling techniques.
141 citations
TL;DR: In this article, the authors compared the power output of the carbon dioxide transcritical cycle and the R125 trans-critical cycle for a low-grade heat source of about 100°C using a simulation method.
132 citations
TL;DR: In this article, a systematic review of the state of the art and challenges in modeling cryogenic heat exchangers is presented, including lumped parameters, distributed parameters and stream-evolution models.
113 citations
TL;DR: In this paper, an alternative method to analyze thermal response tests was developed, which consists in estimating parameters by reproducing the output temperature signal recorded during a test with a numerical groundwater flow and heat transfer model.
103 citations
TL;DR: In this paper, a three dimensional computational fluid dynamics simulation was carried out to understand the effect of simultaneous variation of design parameters, and two functions for the total heat transfer efficiency and the heat exchanger efficiency were derived.
95 citations
TL;DR: In this article, a modular heat exchanger with phase change materials in the shell portion of the module and passage for the flow of air through the tubes was developed for free cooling application where diurnal temperature variation is low.
93 citations
TL;DR: In this paper, a novel design with passive evaporation was introduced for high cooling output, where a rising film evapore coupled with a gravity heat pipe was introduced to improve the performance of a sorption system.
87 citations
TL;DR: In this article, a parametric study of thermodynamic performance on gas turbine power plant was presented, where the variation of operating conditions (compression ratio, turbine inlet and exhaust temperature, air to fuel ratio, isentropic compressor and turbine efficiency, and ambient temperature) on the performance of gas turbine was investigated.
Abstract: This paper was presented the parametric study of thermodynamic performance on gas turbine power plant. The variation of operating conditions (compression ratio, turbine inlet and exhaust temperature, air to fuel ratio, isentropic compressor and turbine efficiency, and ambient temperature) on the performance of gas turbine (thermal efficiency, compressor work, power, specific fuel consumption, heat rate) were investigated. The analytical formula for the specific work and efficiency were derived and analyzed. The programming of performance model for gas turbine was developed utilizing the MATLAB software. The results show that the compression ratio, ambient temperature, air to fuel ratio as well as the isentropic efficiencies are strongly influence on the thermal efficiency. In addition, the thermal efficiency and power output decreases linearly with increase of the ambient temperature and air to fuel ratio. However, the specific fuel consumption and heat rate increases linearly with increase of both ambient temperature and air to fuel ratio. Thus the thermodynamic parameters on cycle performance are economically feasible and beneficial for the gas turbine operations.
83 citations
TL;DR: In this article, the authors defined the heat exchanger thermal resistance based on its entransy dissipation and analyzed various heat exchangers, showing that the minimum entransysy-dissipation-based thermal resistance always corresponds to the highest heat transfer rate.
TL;DR: In this article, a simple approach for the modeling of complex oscillatory thermal-fluid systems capable of converting low grade heat into useful work is presented for the NIFTE, a novel low temperature difference heat utilization technology currently under development.
TL;DR: In this paper, the authors present transient simulation of a domestic ground source heat pump (GSHP) system with a single BHE using a dynamic three-dimensional (3D) numerical BHE model.
Abstract: Common approaches to the simulation of borehole heat exchangers (BHEs) assume heat transfer in circulating fluid and grout to be in a quasi-steady state and ignore fluctuations in fluid temperature due to transport of the fluid around the loop. However, in domestic ground source heat pump (GSHP) systems, the heat pump and circulating pumps switch on and off during a given hour; therefore, the effect of the thermal mass of the circulating fluid and the dynamics of fluid transport through the loop has important implications for system design. This may also be important in commercial systems that are used intermittently. This article presents transient simulation of a domestic GSHP system with a single BHE using a dynamic three-dimensional (3D) numerical BHE model. The results show that delayed response associated with the transit of fluid along the pipe loop is of some significance in moderating swings in temperature during heat pump operation. In addition, when 3D effects are considered, a lower heat trans...
TL;DR: In this article, the optimal design of a multi-pass plate-and-frame heat exchanger with mixed grouping of plates is considered, including the number of passes for both streams, the numbers of plates with different corrugation geometries in each pass, and the plate type and size.
TL;DR: In this article, the use of a high pressure metal hydride (HPMH), Ti 1.1 CrMn, to store hydrogen at high pressures (up to 310 bar) and temperatures below 60°C, conditions that are suitable for automobile fuel cells was explored.
TL;DR: In this article, an analysis of a tubular heat exchanger which utilizes the latent heat of a phase-change material (PCM) is presented, where the PCM melts inside tubes while air flows across the tube banks.
TL;DR: In this article, two different optimization techniques based on first and second law (of thermodynamics) are reported for metal foam heat exchangers, as replacements for finned-tubes in air-cooled condensers of a geothermal power plant.
11 Mar 2011
TL;DR: In this article, the authors present operation and design constraints pertinent to the uses of water and liquid-metal heat pipes in space reactor systems, and the modeling capabilities of the startup from a frozen state.
Abstract: Water and liquid-metal heat pipes are considered for redundant and passive cooling of nuclear reactors and redundant operation of light-weight heat rejection radiators of space reactor power systems. The systems operate continuously for many years independent of the Sun, are enabling of deep space exploration and could provide 10’s of kilowatts of electrical power for lunar and Martian outposts. Space reactors typically operate at 900 K – 1400 K could be cooled using liquid-metal heat pipes with either sodium (900 –1100 K) or lithium (1100 K–1400 K) working fluids. The heat rejection temperatures dictate the working fluid of the radiator heat pipes; potassium for 600 – 800 K, rubidium for 500 – 700 K, and water for < 500 K. These working fluids would be frozen prior to starting up the power systems in orbit or at destination. The startup of water and liquid-metal heat pipes from a frozen state is complex, involving a number of non-linear mass and heat transport processes that require implementing appropriate procedures, depending on the type of working fluid. This paper reviews operation and design constraints pertinent to the uses of water and liquidmetal heat pipes in space reactor systems, and the modeling capabilities of the startup from a frozen state. In addition to models validation, results of design optimization of liquid-metal and water heat pipes in a number of space reactor power systems are presented and discussed.
TL;DR: The numerical results show that the heated surface temperature of porous micro heat sink is low at high heat fluxes and is much less than the bearable temperature level of LED chips.
TL;DR: In this article, a small scale double-reflector solar concentrating system with heat storage was tested and the experimental results demonstrated that the melting of phase change material occurred within 2.5h and reached the temperature range of 230-260°C.
TL;DR: Methods for calibration and potential calibration errors to be avoided are described and publication of results obtained must include data on calibrations and sufficient raw data to assess precision and accuracy of the results.
TL;DR: In this paper, a three-channel 1-1 pass plate heat exchanger (PHE) with sinusoidal wavy surfaces having corrugation angle of 30° was experimentally found.
TL;DR: In this paper, the heat transfer characteristics of supercritical CO2 (S-CO2) fluid in collectors of a solar Rankine cycle system is experimentally investigated at different flow conditions.
TL;DR: In this article, a novel frost-free air-source heat pump system is proposed, the new system can realize heating which does not need defrost in winter, in which extracting heat process from environment includes two steps: the first one is extracting heat from the environment and then to the solution, the second one is releasing heat to the evaporator from the solution.
TL;DR: In this article, a conjugate formulation to predict heat conduction in the solid domain and spray combustion in the fluid domain was developed for multidimensional engine simulation, which can be used to improve engine design for optimal combustion and reduced thermal loading.
TL;DR: In this article, a new class of heat exchanger is proposed for automobile hydrogen storage systems, and a 2D computational model is constructed to explore the thermal and kinetic behavior of the metal hydride.
TL;DR: In this article, the authors considered the optimization of a heat sink formed by parallel circular or non-circular ducts in a finite volume, where the flow is considered to be laminar and steady and the fluid properties are assumed to be constant.
Patent•
07 Nov 2011TL;DR: A waste heat recovery apparatus and process for use with an internal combustion engine includes a thermo electric apparatus that connects to components of the engine to transfer heat between components, generate electric energy from heat extracted from components needing cooling, and convert electric energy to heat energy to transfer to components needing heating as mentioned in this paper.
Abstract: A waste heat recovery apparatus and process for use with an internal combustion engine includes a thermo electric apparatus that connects to components of the internal combustion engine to transfer heat between components, generate electric energy from heat extracted from components needing cooling, and convert electric energy to heat energy to transfer to components needing heating.
TL;DR: In this article, a quasi-3D finite element model of air-ground heat exchanger (AGHX) performance evaluation is presented, together with its validation and research results of conducted simulation.
TL;DR: In this article, the authors used reverse heat loss method to predict the heat transfer characteristics of a residential refrigerator through insulation wall by using the temperature time history characteristics to achieve the steady state condition.