Extensive Parametric Study of Cooling Performance of an Earth-to-Air Heat Exchanger in Hot Semi-Arid Climate

2020 ◽  
Vol 13 (3) ◽  
Author(s):  
Hassan Mahach ◽  
Brahim Benhamou
Keyword(s):  
Parametric Study ◽  
Design Guidelines ◽  
Design Parameters ◽  
Air Cooling ◽  
Cooling Efficiency ◽  
Dynamic Simulations ◽  
Pipe Length ◽  
Hot Climate ◽  
Two Parameters ◽  
Semi Arid

Abstract This work aims to provide some design guidelines for Earth-to-air heat exchangers (EAHX) in hot semi-arid climates. An extensive parametric study in the context of the soil properties and hot climate of Marrakech (Morocco) is carried out considering all the EAHX design parameters that are the EAHX pipe length, number, diameter, spacing, burying depth, and the airflow velocity. More than 400 of the EAHX parameters’ combinations are studied by carrying out more than 400 dynamic simulations using the well-validated TYPE 460 of TRNSYS. Thermal performances of the EAHX are assessed for the air cooling of the buildings by means of “the maximum cooling efficiency,” which is related to the blown air temperature into the building. The results are presented in terms of charts of the cooling efficiency for two parameters at the same time, while the others were set to their reference values. Useful design guidelines, to get air cooled at a set point temperature, are derived.

Parametric Study of an Innovative Counter-Flow Heat Exchanger

2010 ◽  
Author(s):  
Luciano Andrea Catalano ◽  
Fabio De Bellis ◽  
Riccardo Amirante
Keyword(s):  
Heat Exchanger ◽  
Parametric Study ◽  
Particle Diameter ◽  
Solid Particles ◽  
Sensitivity Analyses ◽  
Design Parameters ◽  
Counter Flow ◽  
Pipe Length ◽  
Specific Heats ◽  
High Efficient

An innovative Counter-Flow Sand Heat Exchanger (CFS-HX) is proposed, which makes use of very small solid particles as intermediate medium to perform heat transfer between two gas flows at different temperature. The potential of the CFS-HX was already demonstrated by the authors, both theoretically and experimentally. In this work, a parametric study has been employed in order to explore the capabilities of the proposed heat exchanger. A 1D model (validated by experiments) has been extensively used to perform sensitivity analyses with respect to the major design parameters, i.e.: specific heats, gas and sand densities, particle diameter, prescribed efficiency. Pipe length to obtain a prescribed heat exchanger efficiency has been calculated for a large number of configurations and results have been compared with a baseline case. The proposed computations show that a high efficient heat exchange can be obtained with relatively short pipes and with negligible pressure drop.

Modeling of Micro-Water Gas Shift Reactor Using Integrated Heat Exchange and Reaction Approach

2006 ◽  
Author(s):  
Gap-Yong Kim ◽  
J. Rhett Mayor ◽  
Jun Ni
Keyword(s):  
Heat Exchange ◽  
Parametric Study ◽  
Integrated Approach ◽  
Design Guidelines ◽  
Water Gas Shift ◽  
Design Parameters ◽  
Performance Loss ◽  
Wgs Reaction ◽  
Flow Configurations ◽  
Water Gas

Conventional reactors are large in size and thus have limitations on heat and mass transfer. To overcome these limitations, microreactors have been introduced. This study discusses the development of an integrated reaction and heat exchange approach to microreactor design that enhances reaction yields by allowing the reactant stream to follow optimal reactant temperature profiles. The study details the formulation of two-dimensional model for the integrated reaction and heat exchange reactor design, and applies these models to a parametric study of microreactor designs for the water gas shift (WGS) reaction. The parametric study investigates the sensitivities of design parameters for both the parallel-flow and counter-flow configurations and contributes to establishing general design guidelines for the micro-WGS reactor. The integrated approach achieved significantly higher catalyst utilization when compared to a conventional adiabatic reactor. The study also showed potentials of miniaturizing the reactor by reducing the wall thickness of the reactor without performance loss.

The Design Implications of Chaotic and Near-Chaotic Vibrations in Machines

1998 ◽  
Author(s):  
Pengyun Gu ◽  
Steven Dubowsky ◽  
Constantinos Mavroidis
Keyword(s):  
High Performance ◽  
Chaotic Behavior ◽  
Design Guidelines ◽  
Operating Conditions ◽  
Design Parameters ◽  
Simulation Studies ◽  
Dynamic Simulations ◽  
Dynamic Behaviors ◽  
Chaotic Vibrations ◽  
Accurate Performance

Abstract Accurate performance prediction is key to the design of high performance machines. It is shown here that connection clearance and component flexibility can result in machine dynamic behaviors that are hypersensitive to small variations of system design parameters and operating conditions. These hypersensitivities, which can limit the usefulness of computer dynamic simulations for design, are associated with chaotic and near chaotic behavior. The dynamic behaviors of two systems, an Impact Beam System and a Spatial Slider Crank, are studied. The chaotic vibration of these systems is confirmed numerically and experimentally. Hypersensitivity is shown for both chaotic and periodic response regions, in which case actual dynamic behavior of such machines could be very different in practice from that predicated by design simulation studies. Design guidelines are developed for evaluating the fatigue life and the reliability of machines under these conditions.

Front steering design guidelines formulation for e-scooters considering the influence of sitting and standing riders on self-stability and safety performance

2021 ◽  
pp. 095440702199217
Author(s):  
Milan Paudel ◽  
Fook Fah Yap
Keyword(s):  
Preventive Measures ◽  
Recent Trend ◽  
Dynamic Performance ◽  
Design Guidelines ◽  
Safety Performance ◽  
Design Parameters ◽  
Single Track ◽  
Standing Posture ◽  
Last Mile ◽  
Current Design

E-scooters are a recent trend and are viewed as a sustainable solution to ease the first and last mile problem in modern transportation. However, an alarming rate of accidents, injuries, and fatalities have caused a significant setback for e-scooters. Many preventive measures and legislation have been put on the e-scooters, but the number of accidents and injuries has not reduced considerably. In this paper, the current design approach of e-scooters has been analyzed, and the most common range of design parameters have been identified. Thereafter, validated mathematical models have been used to quantify the performance of e-scooters and relate them with the safety aspects. Both standing and seated riders on e-scooters have been considered, and their influence on the dynamic performance has been analyzed and compared with the standard 26-in wheel reference safety bicycle. With more than 80% of the accidents and injuries occurring from falling or colliding with obstacles, this paper tries to correlate the dynamics of uncontrolled single-track vehicles with the safety performance of e-scooters. The self-stability, handling, and braking effect have been considered as major performance matrices. The analysis has shown that the current e-scooter designs are not as stable as the reference safety bicycle. Moreover, these e-scooters have been found unstable within the most common range of legislated riding velocity. The results corroborate with the general perception that the current designs of e-scooters are less stable, easy to lose control, twitchy, or wobbly to ride. Furthermore, the standing posture of the rider on the e-scooter has been found dangerous while braking to avoid any disturbances such as potholes or obstacles. Finally, the front steering design guidelines have been proposed to help modify the current design of e-scooters to improve the dynamic performance, hence the safety of the e-scooter riders and the surroundings.

Rotor Air-Cooling Efficiency of Powerful Turbogenerator

2020 ◽  
pp. 1-1
Author(s):  
Nikolay Vladimirovich Korovkin ◽  
Dmitry Verkhovtsev ◽  
Stanislav Gulay
Keyword(s):  
Air Cooling ◽  
Cooling Efficiency

Cost Optimum Parameters for Rock Bed Thermal Storage at 550–600 °C: A Parametric Study

2016 ◽  
Vol 138 (6) ◽  
Author(s):  
Kenneth Allen ◽  
Lukas Heller ◽  
Theodor von Backström
Keyword(s):  
Parametric Study ◽  
Particle Diameter ◽  
Thermal Storage ◽  
Design Parameters ◽  
Levelized Cost Of Electricity ◽  
United States Dollar ◽  
Capital Costs ◽  
Mass Fluxes ◽  
Rock Bed ◽  
Biot Numbers

A major advantage of concentrating solar power (CSP) plants is their ability to store thermal energy at a cost far lower than that of current battery technologies. A recent techno-economic study found that packed rock bed thermal storage systems can be constructed with capital costs of less than 10 United States dollar (USD)/kWht, significantly cheaper than the two-tank molten salt thermal storage currently used in CSP plants (about 22–30 USD/kWht). However, little work has been published on determining optimum rock bed design parameters in the context of a CSP plant. The parametric study in this paper is intended to provide an overview of the bed flow lengths, particle sizes, mass fluxes, and Biot numbers which are expected to minimize the levelized cost of electricity (LCOE) for a central receiver CSP plant with a nominal storage capacity of 12 h. The findings show that rock diameters of 20–25 mm will usually give LCOE values at or very close to the minimum LCOE for the combined rock bed and CSP plant. Biot numbers between 0.1 and 0.2 are shown to have little influence on the position of the optimum (with respect to particle diameter) for all practical purposes. Optimum bed lengths are dependent on the Biot number and range between 3 and 10 m for a particle diameter of 20 mm.

Seismic stability analyses of reinforced tapered landfill cover systems considering seepage forces

2018 ◽  
Vol 36 (4) ◽  
pp. 361-372 ◽  
Author(s):  
Afshin Khoshand ◽  
Ali Fathi ◽  
Milad Zoghi ◽  
Hamidreza Kamalan
Keyword(s):  
Parametric Study ◽  
Limit Equilibrium ◽  
Practical Method ◽  
Seismic Stability ◽  
Design Parameters ◽  
Cover System ◽  
Landfill Cover ◽  
Cover Systems ◽  
Landfill Cover System ◽  
The Stability

One of the most common and economical methods for waste disposal is landfilling. The landfill cover system is one of the main components of landfills which prevents waste exposure to the environment by creating a barrier between the waste and the surrounding environment. The stability and integrity of the landfill cover system is a fundamental part of the design, construction, and maintenance of landfills. A reinforced tapered landfill cover system can be considered as a practical method for improving its stability; however, the simultaneous effects of seismic and seepage forces in the reinforced tapered landfill cover system have not been studied. The current paper provides a solution based on the limit equilibrium method in order to evaluate the stability of a reinforced tapered landfill cover system under seismic and seepage (both horizontal and parallel seepage force patterns) loading conditions. The proposed analytical approach is applied to different design cases through parametric study and the obtained results are compared to those derived from literature. Parametric study is performed to illustrate the sensitivity of the safety factor (FS) to the different design parameters. The obtained results reveal that parameters which describe the geometry have limited effects on the stability of the landfill cover system in comparison to the rest of the studied design parameters. Moreover, the comparisons between the derived results and available methods demonstrate good agreement between obtained findings with those reported in the literature.

scholarly journals ARMOUR UNIT STRUCTURAL RESPONSE - A PARAMETRIC STUDY

1988 ◽  
Vol 1 (21) ◽  
pp. 176
Author(s):  
C. David Anglin ◽  
William F. Baird ◽  
Etienne P.D. Mansard ◽  
R. Douglas Scott ◽  
David J. Turcke
Keyword(s):  
Wave Height ◽  
Parametric Study ◽  
Structural Integrity ◽  
Design Procedure ◽  
Structural Response ◽  
Design Parameters ◽  
Coastal Structures ◽  
Log Normal ◽  
Wave Induced ◽  
Hydraulic Stability

There is a general lack of knowledge regarding the nature and magnitude of loads acting on armour units used for the protection of rubblemound coastal structures. Thus, a comprehensive design procedure incorporating both the hydraulic stability and the structural integrity of the armour units does not exist. This paper presents the results of a detailed parametric study of the structural response of armour units to wave-induced loading in a physical breakwater model. The effect of the following design parameters is investigated: breakwater slope, armour unit location, wave period and wave height. This research has made a number of significant contributions towards the development of a comprehensive design procedure for concrete armour units. It has identified a linear relationship between the wave-induced stress in the armour units and the incident wave height. In addition, it has shown that the conditional probability of waveinduced stress given wave height can be estimated by a log-normal distribution. Finally, a preliminary design chart has been developed which incorporates both the structural integrity and the hydraulic stability of the armour units.

Closed-Form Synthesis of Force-Generating Planar Four-Bar Linkages

1995 ◽  
Author(s):  
R. Randall Soper ◽  
Michael Scardina ◽  
Paul Tidwell ◽  
Charles Reinholtz ◽  
Michael A. Lo Presti
Keyword(s):  
Closed Form ◽  
The Other ◽  
Design Parameters ◽  
Synthesis Methods ◽  
Function Generator ◽  
Mechanical Advantage ◽  
Nonlinear Mechanical ◽  
Two Parameters ◽  
Selection Of ◽  
Weight Force

Abstract This paper presents a technique for synthesizing four-bar linkages to produce a specified resisting force or torque. The resisting energy is provided by a weight acting on the other grounded link. The linkage serves as a nonlinear mechanical advantage function generator. Force and velocity synthesis methods have been extensively discussed in the literature. The general approach, however, has been to assume that the specified force or velocity occurs at a prescribed position. This results in the loss of design parameters that are being used unnecessarily to control position. In this application, force input to the linkage is specified as a function of only the input link position and the magnitude and direction of the weight force. Mechanical advantage synthesis can be achieved at as many as seven precision points. The method presented in this paper allows free selection of two parameters and viewing one infinity of solutions.

Origin and formation model of Eocene dolomite in the upper Niubao Formation of Lunpola Basin, Tibetan Plateau

2021 ◽  
pp. 1-50
Author(s):  
Xiaoquan Chen ◽  
Fengcun Xing ◽  
Shu Jiang ◽  
Yongchao Lu ◽  
Zhongrong Liu ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Hot Springs ◽  
Northern China ◽  
Hydrothermal Fluids ◽  
Lake Basin ◽  
The Tibetan Plateau ◽  
Climate Conditions ◽  
Hot Climate ◽  
Strong Evaporation ◽  
Semi Arid

Using fresh cores samples, we determined the origin and formation process of Eocene lacustrine dolomites in the Tibetan Plateau through petrological, mineralogical, and geochemical analyses. Dolomitic rocks were collected from the upper member of Eocene Niubao Formation in the Lunpola Basin, and consist of dolomitic mudstone, argillaceous dolomite, dolomite-bearing mudstone and mud-bearing dolomite. These dolomites are dominated by aphanotopic and micro-crystalline dolomites, with minor amounts of euhedral or subhedral powder- and fine-crystalline dolomites. Carbon and oxygen stable isotopes, combined with ubiquitous gypsum in study area, indicates a semi-saline continental lake under strong evaporative conditions. The revealed relatively high temperature of dolomitization(33.8°C–119.1°C), combined with hydrothermal minerals such as cerous phosphate and barite, reflect the participation of dolomite from hot fluids. Moreover, the inferred dolomitization temperatures decrease gradually toward the centre of the lake basin, suggesting the resurgence of hydrothermal fluids along a fault zone on the lake margin. This proves that frequent thermal events occurred at the boundary fault of the Lunpola Basin margin during early Himalayan orogenesis. In addition, Jurassic carbonates interacting with hydrothermal fluids, as well as strong evaporation conditions, likely provided favourable conditions for the formation of primary lime sediments. A rich source of Mg2+ brought by volcanic ash, hydrothermal fluids, and the Jurassic carbonates then created conditions for dolomitization during the depositional period. Strong evaporation under a relatively hot climate enhanced penecontemporaneous dolomitization, thus forming dolomite. Tibetan Plateau was under arid to semi-arid climate conditions, and there was a widespread distribution of dolostones in western, central, and northern China during the Eocene period. The hydrothermal dolomites of the upper Niubao Formation testify for active hot springs, while lacustrine dolomite imply arid or semi-arid climates during the Eocene, in the early stages of Himalayan orogenesis.

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