Parametric Study of an Innovative Counter-Flow Heat Exchanger

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.

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

Journal of Solar Energy Engineering ◽

10.1115/1.4034334 ◽

2016 ◽

Vol 138 (6) ◽

Cited By ~ 1

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.

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Thermal-economic multiobjective optimization of heat pipe heat exchanger for energy recovery in HVAC applications using genetic algorithm

Thermal Science ◽

10.2298/tsci111024203s ◽

2014 ◽

Vol 18 (suppl.2) ◽

pp. 375-391 ◽

Cited By ~ 4

Author(s):

Sepehr Sanaye ◽

Davood Modarrespoor

Keyword(s):

Genetic Algorithm ◽

Heat Exchanger ◽

Heat Pipe ◽

Operating Cost ◽

Design Parameters ◽

Nsga Ii ◽

Pipe Length ◽

Total Cost ◽

Continuous And Discrete Variables ◽

Pipe Heat

Cost and effectiveness are two important factors of heat pipe heat exchanger (HPHE) design. The total cost includes the investment cost for buying equipment (heat exchanger surface area) and operating cost for energy expenditures (related to fan power). The HPHE was thermally modeled using e-NTU method to estimate the overall heat transfer coefficient for the bank of finned tubes as well as estimating pressure drop. Fast and elitist non-dominated sorting genetic algorithm (NSGA-II) with continuous and discrete variables was applied to obtain the maximum effectiveness and the minimum total cost as two objective functions. Pipe diameter, pipe length, numbers of pipes per row, number of rows, fin pitch and fin length ratio were considered as six design parameters. The results of optimal designs were a set of multiple optimum solutions, called ?Pareto optimal solutions?. The comparison of the optimum values of total cost and effectiveness, variation of optimum values of design parameters as well as estimating the payback period were also reported for various inlet fresh air volume flow rates.

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

Journal of Thermal Science and Engineering Applications ◽

10.1115/1.4047945 ◽

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.

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Effect of vibrator position and frequency on heat transfer enhancement in counter flow concentric pipe heat exchanger

World Journal of Engineering ◽

10.1108/wje-01-2020-0032 ◽

2020 ◽

Vol 17 (5) ◽

pp. 751-760

Author(s):

Shanmukh Sudhir Arasavelli ◽

Ramakrishna Konijeti ◽

Govinda Rao Budda

Keyword(s):

Heat Transfer ◽

Nusselt Number ◽

Heat Exchanger ◽

Heat Transfer Enhancement ◽

Hot Water ◽

Transfer Enhancement ◽

Counter Flow ◽

Pipe Length ◽

Content Type ◽

Pipe Heat

Purpose This paper aims to deal with heat transfer enhancement because of transverse vibration on counter flow concentric pipe heat exchanger. Experiments were performed at different vibrator positions with varying amplitudes and frequencies. Design/methodology/approach Tests are carried out at 4 different vibration frequencies (20, 40, 60 and 100 Hz), 3 vibration amplitudes (23, 46 and 69 mm) and at 3 vibrator positions (1/4, 1/2 and 3/4 of pipe length) with respect to hot water inlet under turbulent flow condition. Findings Experimental results indicate that Nusselt number is enhanced to a maximum extent of 44% with vibration when compared to Nusselt number without vibration at a frequency of 40 Hz, an amplitude of 69 mm and at a vibrator position of one-fourth of pipe length with respect to hot water inlet. Originality/value Empirical correlation is developed from experimental data to estimate the heat transfer coefficient with vibration for experimental frequency range with an error estimate of approximately ±10%.

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Isentropic recuperative heat exchanger with regenerative work transfer

Proceedings of the Institution of Mechanical Engineers Part C Journal of Mechanical Engineering Science ◽

10.1243/0954406001523948 ◽

2000 ◽

Vol 214 (4) ◽

pp. 609-618 ◽

Cited By ~ 2

Author(s):

H V Rao

Keyword(s):

Heat Transfer ◽

Heat Exchanger ◽

Counter Flow ◽

Specific Heats ◽

Flow Heat ◽

Recuperative Heat Exchanger ◽

The Relationship ◽

Ideal Method ◽

Two Fluid ◽

The Ideal

A counter-flow heat exchanger is considered to be the ideal method for recuperative heat transfer between hot and cold fluid streams. In this paper the concept of an isentropic heat exchanger with regenerative work transfer is developed. The overall effect is a mutual heat transfer between the two fluid streams without any net external heat or work transfers. The effectiveness for an isentropic heat exchanger with regenerative work transfer is derived for the case of fluid streams with constant specific heats and it is shown that it is greater than unity. The ‘isentropic effectiveness’ of a heat exchanger is defined. The relationship between the entropy generation and effectiveness for the traditional heat exchanger is also examined and compared with that of the isentropic heat exchanger. The practical realization of isentropic operation of a heat exchanger and its possible application are briefly considered.

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Geotechnical Considerations in the Design of Borehole Heat Exchangers

Canadian Geotechnical Journal ◽

10.1139/cgj-2020-0118 ◽

2020 ◽

Author(s):

Despina Maria Zymnis ◽

Andrew J. Whittle

Keyword(s):

Heat Exchanger ◽

Parametric Study ◽

Heat Exchangers ◽

Design Parameters ◽

Ground Source Heat Pumps ◽

Heat Exchanger Design ◽

Heating And Cooling ◽

Adjacent Structures ◽

Borehole Heat Exchangers

The use of ground source heat pumps to transfer heat to and from the ground via borehole heat exchangers (BHE) is among the most energy efficient techniques for space heating and cooling. Broader applications in urban environments require more careful evaluation of hydro-mechanical behavior of soil to ensure their reliable long-term performance and to minimize adverse effects on adjacent structures. An advanced soil model has been integrated within a finite difference (FD) framework, to solve coupled thermo-hydro-mechanical (THM) problems in an axisymmetric space. The FD simulator is applied to a prototype project and the ground conditions represent typical stress history profiles found in Geneva, Switzerland. An extensive parametric study is undertaken to study the long-term THM response of clay for a broad range of heat exchanger design parameters. The results show that significant settlements can be induced due to the long-term operation of BHEs (i.e., over periods from 10–50 years). The parametric study gives useful guidelines for heat exchanger design and identifies a design space of optimum solutions that meet pre-specified foundation settlement criteria. The study provides a qualitative investigation and a systematic framework for analyzing the long-term THM response of clay to seasonal heating and cooling.

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