scholarly journals Study of Various Configurations of Hybrid PV/T System

2021 ◽  
Vol 8 ◽  
pp. 62-69
Author(s):  
H. Ben Cheikh El Hocine ◽  
M. Marir-Benabbas
Keyword(s):  
Heat Removal ◽  
Heat Extraction ◽  
Design Parameters ◽  
Back Surface ◽  
Extraction Operation ◽  
Performance And Evaluation ◽  
Dual Extraction ◽  
Water Collector ◽  
Analytical Expressions ◽  
T System

In this study, an attempt has been made to evaluate the theoretical performance and evaluation of a hybrid PV/thermal (PV/T) collector based on dual heat extraction operation a function of climatic and design parameters. On the first hand, the different configurations of hybrid collectors are considered for the present study which are defined as unglazed PV/T air heaters, with and without tedlar, PVT hybrid water collector, in the second hand two configurations with dual extraction operation (water and air as heat removal fluid) are presented which are defined as dual PV/T model with tedlar, dual hybrid PV/T without tedlar. Analytical expressions for the temperatures of solar cells, back surface of the module, outlet air, and outlet water of those configurations have been derived. Numerical computations have been carried out for composite climate and the results for different configurations have been compared. Our results clearly show the direct impact of various parameters, in particular the solar radiation, ambient temperature, mass flow rate on the variation of outlet and solar cell of the collector.

A Simplified Design Model for Modular Steel Buildings Subject to Vapor Cloud Explosions (VCEs)

2020 ◽  
Vol 14 ◽  
Author(s):  
Osama Bedair
Keyword(s):  
Dynamic Response ◽  
Minimum Cost ◽  
Design Parameters ◽  
Front Wall ◽  
Steel Buildings ◽  
Element Analysis ◽  
Analysis And Design ◽  
Vapor Cloud ◽  
Building Components ◽  
Analytical Expressions

Background: Modular steel buildings (MSB) are extensively used in petrochemical plants and refineries. Limited guidelines are available in the industry for analysis and design of (MSB) subject to accidental vapor cloud explosions (VCEs). Objectives: The paper presents simplified engineering model for modular steel buildings (MSB) subject to accidental vapor cloud explosions (VCEs) that are extensively used in petrochemical plants and refineries. Method: A Single degree of freedom (SDOF) dynamic model is utilized to simulate the dynamic response of primary building components. Analytical expressions are then provided to compute the dynamic load factors (DLF) for critical building elements. Recommended foundation systems are also proposed to install the modular building with minimum cost. Results: Numerical results are presented to illustrate the dynamic response of (MSB) subject to blast loading. It is shown that (DLF)=1.6 is attained at (td/t)=0.4 for front wall (W1) with (td/T)=1.25. For side walls (DLF)=1.41 and is attained at (td/t)=0.6. Conclusions: The paper presented simplified tools for analysis and design of (MSB) subject accidental vapor cloud blast explosions (VCEs). The analytical expressions can be utilized by practitioners to compute the (MSB) response and identify the design parameters. They are simple to use compared to Finite Element Analysis.

Analytical Model of the Efficiency of Spur Gears: Study of the Influence of the Design Parameters

2011 ◽  
Author(s):  
Miguel Pleguezuelos ◽  
Jose´ I. Pedrero ◽  
Miryam B. Sa´nchez
Keyword(s):  
Load Distribution ◽  
Gear Ratio ◽  
Design Parameters ◽  
Spur Gears ◽  
Transmitted Power ◽  
Power Losses ◽  
Contact Ratio ◽  
Complete Study ◽  
Uniform Model ◽  
Analytical Expressions

An analytic model to compute the efficiency of spur gears has been developed. It is based on the application of a non-uniform model of load distribution obtained from the minimum elastic potential criterion and a simplified non-uniform model of the friction coefficient along the path of contact. Both conventional and high transverse contact ratio spur gears have been considered. Analytical expressions for the power losses due to friction, for the transmitted power and for the efficiency are presented. From this model, a complete study of the influence of some design parameters (as the number of teeth, the gear ratio, the pressure angle, the addendum modification coefficient, etc.) on the efficiency is presented.

Direct Liquid Cooling of High Flux LED Systems: Hot Spot Abatement

2013 ◽  
Author(s):  
Enes Tamdogan ◽  
Mehmet Arik ◽  
M. Baris Dogruoz
Keyword(s):  
Hot Spots ◽  
Hot Spot ◽  
Heat Removal ◽  
Heat Fluxes ◽  
Light Extraction ◽  
Junction Temperature ◽  
System Level ◽  
Design Parameters ◽  
Liquid Cooling ◽  
Wide Range

With the recent advances in wide band gap device technology, solid-state lighting (SSL) has become favorable for many lighting applications due to energy savings, long life, green nature for environment, and exceptional color performance. Light emitting diodes (LED) as SSL devices have recently offered unique advantages for a wide range of commercial and residential applications. However, LED operation is strictly limited by temperature as its preferred chip junction temperature is below 100 °C. This is very similar to advanced electronics components with continuously increasing heat fluxes due to the expanding microprocessor power dissipation coupled with reduction in feature sizes. While in some of the applications standard cooling techniques cannot achieve an effective cooling performance due to physical limitations or poor heat transfer capabilities, development of novel cooling techniques is necessary. The emergence of LED hot spots has also turned attention to the cooling with dielectric liquids intimately in contact with the heat and photon dissipating surfaces, where elevated LED temperatures will adversely affect light extraction and reliability. In the interest of highly effective heat removal from LEDs with direct liquid cooling, the current paper starts with explaining the increasing thermal problems in electronics and also in lighting technologies followed by a brief overview of the state of the art for liquid cooling technologies. Then, attention will be turned into thermal consideration of approximately a 60W replacement LED light engine. A conjugate CFD model is deployed to determine local hot spots and to optimize the thermal resistance by varying multiple design parameters, boundary conditions, and the type of fluid. Detailed system level simulations also point out possible abatement techniques for local hot spots while keeping light extraction at maximum.

A Computational Model for Performance Prediction of a Hybrid PV/T Module

2014 ◽  
Author(s):  
Francisco E. Zevallos ◽  
Cheng-Xian Lin ◽  
Robel Kiflemariam
Keyword(s):  
Computational Simulation ◽  
Thermal Design ◽  
Simulation Program ◽  
Back Surface ◽  
Solar Photovoltaic ◽  
Analytical Expression ◽  
Pv Module ◽  
Computer Simulation Program ◽  
Water Collector ◽  
Instantaneous Energy

In this paper we investigate the performance of an integrated solar photovoltaic and thermal (PV/T) liquid (water) collector using a computational simulation program. A detailed time-dependent thermal model was formulated to calculate and correlate the thermal parameters in a standard PV/T collector, including solar cell temperature, back surface temperature, and outlet water temperature. Based on the energy balance of each component of the system, an analytical expression for the temperature of the PV module and the water was derived. In addition, an analytical expression for the instantaneous energy efficiency of the PV/T collector was also derived in terms of thermal, design and climatic parameters. Built on previously published model, a new computer simulation program was developed and validated. The thermal simulation results obtained are more precise than those previously reported in the literature.

Turret Mooring Design Based on Analytical Expressions of Catastrophes of Slow-Motion Dynamics

1998 ◽  
Vol 120 (3) ◽  
pp. 154-164 ◽  
Author(s):  
M. M. Bernitsas ◽  
L. O. Garza-Rios
Keyword(s):  
Parametric Design ◽  
Dynamical Behavior ◽  
Three Dimensional ◽  
Slow Motion ◽  
Sensitivity Analyses ◽  
Design Parameters ◽  
Mooring Lines ◽  
The Stability ◽  
Fifth Order ◽  
Analytical Expressions

Analytical expressions of the bifurcation boundaries exhibited by turret mooring systems (TMS), and expressions that define the morphogeneses occurring across boundaries are developed. These expressions provide the necessary means for evaluating the stability of a TMS around an equilibrium position, and constructing catastrophe sets in two or three-dimensional parametric design spaces. Sensitivity analyses of the bifurcation boundaries define the effect of any parameter or group of parameters on the dynamical behavior of the system. These expressions allow the designer to select appropriate values for TMS design parameters without resorting to trial and error. A four-line TMS is used to demonstrate this design methodology. The mathematical model consists of the nonlinear, fifth-order, low-speed, large-drift maneuvering equations. Mooring lines are modeled with submerged catenaries, and include nonlinear drag. External excitation consists of time-independent current, wind, and mean wave drift.

Multidisciplinary Analysis of a Geared Fan Intercooled Core Aero-Engine

2013 ◽  
Vol 136 (1) ◽  
Author(s):  
Konstantinos G. Kyprianidis ◽  
Andrew M. Rolt ◽  
Tomas Grönstedt
Keyword(s):  
Exchange Rates ◽  
Fuel Consumption ◽  
Pressure Ratio ◽  
Velocity Ratio ◽  
Specific Fuel Consumption ◽  
Design Parameters ◽  
Aircraft Model ◽  
Aero Engine ◽  
Jet Velocity ◽  
Analytical Expressions

The reduction of CO2 emissions is strongly linked with the improvement of engine specific fuel consumption, along with the reduction of engine nacelle drag and weight. One alternative design approach to improving specific fuel consumption is to consider a geared fan combined with an increased overall pressure ratio intercooled core performance cycle. The thermal benefits from intercooling have been well documented in the literature. Nevertheless, there is very little information available in the public domain with respect to design space exploration of such an engine concept when combined with a geared fan. The present work uses a multidisciplinary conceptual design tool to analyze the option of an intercooled core geared fan aero engine for long haul applications with a 2020 entry into service technology level assumption. With minimum mission fuel in mind, the results indicate as optimal values a pressure ratio split exponent of 0.38 and an intercooler mass flow ratio of 1.18 at hot-day top of climb conditions. At ISA midcruise conditions a specific thrust of 86 m/s, a jet velocity ratio of 0.83, an intercooler effectiveness of 56%, and an overall pressure ratio value of 76 are likely to be a good choice. A 70,000 lbf intercooled turbofan engine is large enough to make efficient use of an all-axial compression system, particularly within a geared fan configuration, but intercooling is perhaps more likely to be applied to even larger engines. The proposed optimal jet velocity ratio is actually higher than the value one would expect by using standard analytical expressions, primarily because this design variable affects core efficiency at mid-cruise due to a combination of several different subtle changes to the core cycle and core component efficiencies at this condition. The analytical expressions do not consider changes in core efficiency and the beneficial effect of intercooling on transfer efficiency, nor do they account for losses in the bypass duct and jet pipe, while a relatively detailed engine performance model, such as the one utilized in this study, does. Mission fuel results from a surrogate model are in good agreement with the results obtained from a rubberized-wing aircraft model for some of the design parameters. This indicates that it is possible to replace an aircraft model with specific fuel consumption and weight penalty exchange rates. Nevertheless, drag count exchange rates have to be utilized to properly assess changes in mission fuel for those design parameters that affect nacelle diameter.

A source-sink approach for computation of intensity of low-potential underground heat non-stationary extraction

2020 ◽  
Vol 5 ◽  
pp. 28-36
Author(s):  
Dmitry Saponenko ◽  
Boris Semenov
Keyword(s):  
Heat Transfer ◽  
Heat Removal ◽  
Heat Extraction ◽  
Transfer Resistance ◽  
Intensity Estimation ◽  
Linear Heat ◽  
Ground Types ◽  
Single Pipe ◽  
Source Sink ◽  
Stationary Heat Transfer

A new methodology for estimation of changing intensity characteristics of non-stationary heat transfer in underground heat extraction by a single-pipe upright heat exchanger is presented in this paper. Major trends in changing of a heat removal volume, linear heat transfer coefficient, linear heat transfer resistance, and heat sink radius have been estimated for specific ground types. Also a generalized one-factor linear semilogarythmic equation has been developed for specific ground types, along with an appropriate approximating function intended to simplify the underground heat extraction intensity estimation methodology.

Optimization Design for Air Heat Exchanger of Large Fast Reactor Based on Genetic Algorithm

2013 ◽  
Author(s):  
Huajin Yu ◽  
Lina Zhu ◽  
Zhenxing Zhang ◽  
Ziyu Liao
Keyword(s):  
Genetic Algorithm ◽  
Heat Exchanger ◽  
Fast Reactor ◽  
Optimization Design ◽  
Heat Removal ◽  
Tube Length ◽  
Design Parameters ◽  
Shell Side ◽  
Air Resistance ◽  
Fin Tube

The passive design for decay heat removal system of future fast reactor will put forward higher requirement for air heat exchanger (AHX), which is directly relevant to the structure and anti-seismic design of stack. Under considering the heat exchanger ability and the structure compactness comprehensively, a strategy for the optimization design of AHX based on genetic algorithm was developed in this paper. The air resistance in shell side of vertical fin tube AHX was chosen as the objective function, and the effect of design parameters including fin pitch, number of tube rows, tube pitch and tube length on the air resistance was discussed. The results of the study show that the method for the optimization design of AHX based on genetic algorithm can effectively optimize the structure of AHX and improve the resistance characteristic of the shell side evidently, which leads to design the fast reactor plant, stack structure and seismic resistance simply.

scholarly journals Effects of Heat Removal Through the Hand on Metabolism and Performance During Cycling Exercise in the Heat

2005 ◽  
Vol 30 (1) ◽  
pp. 87-104 ◽  
Author(s):  
Andrew R. Hsu ◽  
Todd A. Hagobian ◽  
Kevin A. Jacobs ◽  
Hamdee Attallah ◽  
Anne L. Friedlander
Keyword(s):  
Core Temperature ◽  
Performance Test ◽  
Lactate Concentration ◽  
Heat Removal ◽  
Time Trial ◽  
The Body ◽  
Heat Extraction ◽  
Time Trial Performance ◽  
Ergometer Exercise ◽  
Trial Performance

Objective: This two-part study tested the hypotheses that the use of a new cooling device, purported to extract heat from the body core through the palm of the hand, would (a) attenuate core temperature rise during submaximal exercise in the heat, thereby suppressing exercise-associated metabolic changes, and (b) facilitate a higher sustained workload, thus shortening the completion time of a time-trial performance test. Methods: In Study 1, 8 male triathletes (age 27.9 ± 2.0 yrs, mass 77.2 ± 3.1 kg, [Formula: see text]Peak 59.0 ± 4.1 ml•min−1•kg−1) cycled for 1 hr at the same absolute workload (∼60% [Formula: see text]peak) in a heated room (31.9 ± 0.1 °C, 24 ±1% humidity) on two occasions counterbalanced for cooling (C) or noncooling (NC). In Study 2, 8 similar subjects (age 26.9 ± 2.0 yrs, mass 75.2 ± 3.7 kg, [Formula: see text]peak 54.1 ± 3.1 ml•min−1•kg−1) performed two 30-km cycling time-trial performance tests under the same conditions (CT NCT). Results: In Study 1, cooling attenuated the rise in tympanic temperature (TTY) (1.2 ± 0.2 vs. 1.8 ± 0.2 °C; p <  0.01) and lowered mean oxygen consumption ([Formula: see text] 2.4 ± 0.1 vs. 2.7 ± 0.1 L•min−1; p <  0.05) and blood lactate (1.7 ± 0.2 vs. 2.2 ± 0.2 mmol. L−1; p <  0.01) during exercise. There were no significant differences in respiratory exchange ratio (RER), blood glucose, heart rate (HR), face temperature (TF), or back temperature (TB) between NC and C. In Study 2, time to complete 30 km was 6 ± 1% less with cooling than without cooling (60.9 ± 2.0 vs. 64.9 ± 2.6 min; p <  0.01). During the last 20% of CT, subjects sustained a workload that was 14 ± 5% (p = 0.06) higher than NCT at the same TTY and HR. Conclusions: Heat extraction through the hand during cycle ergometer exercise in the heat can (a) lower TTY, lactate concentration, and [Formula: see text] during a submaximal set-workload test and (b) reduce the time it takes to complete a 30-km time-trial test. Key words: core temperature, hyperthermia, thermoregulation, hand-cooling

scholarly journals Computational Simulation and Analysis of Major Control Parameters of Time-Dependent PV/T Collectors

2019 ◽  
Author(s):  
Jimeng Shi ◽  
Cheng-Xian Lin
Keyword(s):  
Solar Cell ◽  
Thermal Model ◽  
Computational Simulation ◽  
Back Surface ◽  
Control Parameters ◽  
Pv Module ◽  
Crystalline Solar Cell ◽  
Relationship Of ◽  
The Relationship ◽  
T System

Abstract In order to improve performance of photovoltaic/thermal (or PV/T for simplicity) collectors, this paper firstly validated a previous computational thermal model and then introduced an improved computational thermal model to investigate the effects of the major control parameters on the thermal performance of PV/T collectors, including solar cell temperature, back surface temperature, and outlet water temperature. Besides, a computational electrical model of PV/T system was also introduced to elaborate the relationship of voltage, current and power of a PV module (MSX60 poly-crystalline solar cell) used in an experiment in the literature. Simulation results agree with the experimental data very well. The effects of the time-steps from 1 hour to minute, which is closed to the real time, were also reported. At last, several suggestions to improve the efficiency of PV/T system were illustrated.

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