On the Merkel Equation: Novel ε-Number of Transfer Unit Correlations for Indirect Evaporative Cooler Under Different Lewis Numbers

2017 ◽  
Vol 9 (4) ◽  
Author(s):  
M. Khamis Mansour
Keyword(s):  
Present Model ◽  
Cooling Tower ◽  
Numerical Models ◽  
Thermal Design ◽  
Numerical Work ◽  
New Model ◽  
General Integral ◽  
Transfer Unit ◽  
Evaporative Cooler ◽  
And Performance

An innovative relationship between the effectiveness (ε) and number of transfer unit (NTU) was presented in this work for indirect evaporative cooler (IEC). This relationship is featured by its simplicity in use and has noniterative procedure to be implemented as the traditional one in the literature. The new model can be implemented in sizing and rating design of the IEC at different Lewis numbers with a reasonable accuracy. General integral equation, which is similar to that of Merkel equation, is developed in this model. The new relationship was verified through comparison with experimental and numerical work reported in the available literature for closed or indirect cooling tower (ICT), as an example of IEC. Additionally, the predicted results of the present model were compared to those obtained from the traditional numerical models at different Lewis numbers. The simulated results from the new model show a satisfactory agreement with those obtained from the experimental work of less than 10%. The new correlations can be implemented easily in predicting the thermal design and performance of IEC in any simulation program or in real site.

Monitoring and Performance Evaluation of Plastic Cleanup Systems: Part I — Description of the Experimental Campaign

2020 ◽  
Author(s):  
Bruno Sainte-Rose ◽  
Hendrik Wrenger ◽  
Hans Limburg ◽  
Arthur Fourny ◽  
Arjen Tjallema
Keyword(s):  
Environmental Conditions ◽  
Performance Indicator ◽  
Numerical Models ◽  
Numerical Work ◽  
Surface Transport ◽  
Experimental Campaign ◽  
Convergence Zones ◽  
Field Efficiency ◽  
And Performance ◽  
The One

Abstract The Ocean Cleanup Foundation is developing floating barrier systems to concentrate and extract buoyant plastic from the global accumulation zones located in the subtropical convergence zones in the world’s oceans. In that context, two cleanup systems have been designed, built and deployed in the Great Pacific Garbage Patch since 2018 to evaluate their performance in the field. During those campaigns, a large amount of data in terms of system displacement and environmental conditions has been collected. This data serves to further validate and calibrate numerical models that will be used to develop future generations of cleanup systems. The main performance indicator in scrutiny is the field efficiency which can be derived from on the one hand the barrier horizontal motion in terms of displacement and span heading and on the other hand the plastic transport around and inside the barrier. This information then needs to be correlated to the background environmental conditions to evaluate the barrier’s efficiency over a longer deployment period and allow multi-decadal hindcast analysis. describe both the experimental and numerical work, this paper is split in two parts. This first part is dedicated to the presentation of the experimental setup in terms of barrier displacement, environmental conditions and surface transport measurements. This paper details the techniques employed to carry out those measurements, how they are processed but also the short comings of some measurement methods.

Design of Optimum Plate-Fin Natural Convective Heat Sinks

2003 ◽  
Vol 125 (2) ◽  
pp. 208-216 ◽  
Author(s):  
Avram Bar-Cohen ◽  
Madhusudan Iyengar ◽  
Allan D. Kraus
Keyword(s):  
Nusselt Number ◽  
Specific Heat ◽  
Rectangular Plate ◽  
Heat Sink ◽  
Heat Dissipation ◽  
Thermal Design ◽  
Heat Sinks ◽  
And Performance ◽  
Nusselt Number Correlation ◽  
The Impact

The effort described herein extends the use of least-material single rectangular plate-fin analysis to multiple fin arrays, using a composite Nusselt number correlation. The optimally spaced least-material array was also found to be the globally best thermal design. Comparisons of the thermal capability of these optimum arrays, on the basis of total heat dissipation, heat dissipation per unit mass, and space claim specific heat dissipation, are provided for several potential heat sink materials. The impact of manufacturability constraints on the design and performance of these heat sinks is briefly discussed.

Design and Control of Bypass Condensers

2012 ◽  
Author(s):  
Ranga Nadig ◽  
Michael Phipps
Keyword(s):  
Thermal Design ◽  
Waste To Energy ◽  
Inlet Temperature ◽  
Circulating Water ◽  
Large Shell ◽  
Small Tube ◽  
And Performance ◽  
And Control ◽  
Proper Performance ◽  
Energy Plants

In waste to energy plants and certain genre of cogeneration plants, it is mandatory to condense the steam from the boiler or HRSG in a separate bypass condenser when the steam turbine is out of service. The steam from the boiler or HRSG is attemperated in a pressure reducing desuperheating valve and then condensed in a bypass condenser. To avoid flashing of condensate in downstream piping it is customary to subcool the condensate in the bypass condenser. Circulating water from the steam surface condenser is used to condense the steam in the bypass condenser. Some of the challenges involved in the design of the bypass condenser are: • High shellside design pressure and temperature • Condensate subcooling • Large circulating water (tubeside) flow rate • Relatively low circulating water (tubeside) inlet temperature • Large Log Mean Temperature Difference (LMTD) • Large shell diameters • Small tube lengths The diverse requirements complicate the mechanical and thermal design of the bypass condenser. This paper highlights the complexities in the design and performance of the bypass condenser. Similarities with the design and operation of steam surface condensers and feedwater heater are reviewed. The uniqueness of the bypass condenser’s design and operation are discussed and appropriate solutions to ensure proper performance are suggested.

Advanced Cooling Tower Concept for Commercial and Industrial Applications

2014 ◽  
Author(s):  
Sergey Anisimov ◽  
Aleksandr Kozlov ◽  
Paul Glanville ◽  
Mark Khinkis ◽  
Valeriy Maisotsenko ◽  
...  
Keyword(s):  
Cooling Tower ◽  
Industrial Applications ◽  
Process Efficiency ◽  
Limiting Factor ◽  
Cooling Towers ◽  
Water Stream ◽  
Cooling Performance ◽  
Evaporative Cooler ◽  
Direct Evaporative Cooler ◽  
The U.S

For the majority of cooling towers installed, of which there are greater than half a million installed in the U.S., tower design uses direct evaporative cooler technology where an ideally enthalpy-neutral process cools the process water stream to a temperature above the ambient wet bulb. This ambient wet bulb temperature is the limiting factor for the process cooling. As such the energy-water connection is clear, these cooling towers are direct consumers of treated water and their cooling performance is intimately tied to the process efficiency.

scholarly journals Experimental Assessment of Flow, Performance, and Loads for Tidal Turbines in a Closely-Spaced Array

Energies ◽  
2020 ◽  
Vol 13 (8) ◽  
pp. 1977 ◽  
Author(s):  
Donald R. Noble ◽  
Samuel Draycott ◽  
Anup Nambiar ◽  
Brian G. Sellar ◽  
Jeffrey Steynor ◽  
...  
Keyword(s):  
Numerical Models ◽  
Ocean Energy ◽  
Complex Flow ◽  
Flow Measurements ◽  
Power Extraction ◽  
Tidal Turbines ◽  
Tidal Stream ◽  
Flow Through ◽  
And Performance ◽  
Structural Loading

Tidal stream turbines are subject to complex flow conditions, particularly when installed in staggered array configurations where the downstream turbines are affected by the wake and/or bypass flow of upstream turbines. This work presents, for the first time, methods for and results from the physical testing of three 1/15 scale instrumented turbines configured in a closely-spaced staggered array, and demonstrates experimentally that increased power extraction can be achieved through reduced array separation. A comprehensive set of flow measurements was taken during several weeks testing in the FloWave Ocean Energy Research Facility, with different configurations of turbines installed in the tank in a current of 0.8 m/s, to understand the effect that the front turbines have on flow through the array and on the inflow to the centrally placed rearmost turbine. Loads on the turbine structure, rotor, and blade roots were measured along with the rotational speed of the rotor to assess concurrently in real-time the effects of flow and array geometry on structural loading and performance. Operating in this closely-spaced array was found to improve the power delivered by the rear turbine by 5.7–10.4% with a corresponding increase in the thrust loading on the rotor of 4.8–7.3% around the peak power operating point. The experimental methods developed and results arising from this work will also be useful for further scale-testing elsewhere, validating numerical models, and for understanding the performance and loading of full-scale tidal stream turbines in arrays.

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