Application of Direct Evaporative Coolers for Improving the Energy Efficiency of Air-Cooled Chillers

2005 ◽  
Vol 127 (3) ◽  
pp. 430-433 ◽  
Author(s):  
F. W. Yu ◽  
K. T. Chan
Keyword(s):  
Energy Efficiency ◽  
Simulation Analysis ◽  
Pressure Control ◽  
Operating Conditions ◽  
Outdoor Air ◽  
Air Cooled Condensers ◽  
Head Pressure ◽  
Evaporative Cooler ◽  
Compressor Power ◽  
Direct Evaporative Cooler

This paper describes how direct evaporative coolers can be used to improve the energy efficiency of air-cooled chillers in various operating conditions and with different strategies for staging condenser fans. These coolers are installed in front of air-cooled condensers to precool outdoor air before entering the condensers. A simulation analysis on an air-cooled chiller equipped with a direct evaporative cooler showed that when head pressure control is used, the cooler enables the condensing temperature to drop by 2.1–6.2°C, resulting in a 1.4-14.4% decrease in chiller power and a 1.3–4.6% increase in the refrigeration effect. When the chiller with the cooler operates under condensing temperature control, where condenser effectiveness is enhanced by staging all condenser fans, there is a savings in chiller power of 1.3-4.3% in some operating conditions in which the drop in compressor power exceeds the additional condenser fan power due to the pressure drop across the cooler.

scholarly journals Energy Performance Comparison between Two Liquid Desiccant and Evaporative Cooling-Assisted Air Conditioning Systems

Energies ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 522
Author(s):  
Su Liu ◽  
Jae-Weon Jeong
Keyword(s):  
Energy Consumption ◽  
Air Conditioning ◽  
Evaporative Cooling ◽  
Dew Point ◽  
Outdoor Air ◽  
Liquid Desiccant ◽  
Energy Saving Potential ◽  
Evaporative Cooler ◽  
Air Conditioning Systems ◽  
Direct Evaporative Cooler

This study investigated the annual energy saving potential and system performance of two different evaporative cooling-based liquid desiccant and evaporative cooling-assisted air conditioning systems. One system used an indirect and direct evaporative cooler with a two-stage package to match the target supply air point. The other was equipped with a single-stage, packaged dew-point evaporative cooler that used a portion of the process air, which had been dehumidified in advance. Systems installed with the two evaporative coolers were compared to determine which one was more energy efficient and which one could provide better thermal comfort for building occupants in a given climate zone, using detailed simulation data. The detailed energy consumption data of these two systems were estimated using an engineering equation solver with each component model. The results showed that the liquid desiccant and dew-point evaporative-cooler-assisted 100% outdoor air system (LDEOAS) resulted in approximately 34% more annual primary energy consumption than that of the liquid desiccant and the indirect and direct evaporative-cooler-assisted 100% outdoor air system (LDIDECOAS). However, the LDEOAS could provide drier and cooler supply air, compared with the LDIDECOAS. In conclusion, LDIDECOAS has a higher energy saving potential than LDEOAS, with an acceptable level of thermal comfort.

Heat Exchanger Design of Direct Evaporative Cooler Based on Outdoor and Indoor Environmental Conditions

2014 ◽  
Vol 6 (4) ◽  
Author(s):  
Neda Gilani ◽  
Amin Haghighi Poshtiri
Keyword(s):  
Heat Exchanger ◽  
Thermal Comfort ◽  
Indoor Air ◽  
Ambient Air ◽  
Operating Conditions ◽  
Design Guideline ◽  
Heat Exchanger Design ◽  
Evaporative Cooler ◽  
Direct Evaporative Cooler ◽  
Comfort Criteria

Performance of a direct evaporative cooler (DEC) was numerically studied at various outdoor and indoor air conditions, with geometric and physical characteristics of it being extracted based on thermal comfort criteria. For this purpose, a mathematical model was utilized based on the equations of mass, momentum, and energy conservation to determine heat and mass transfer characteristics of the system. It is found that the DEC can provide thermal comfort conditions when the outdoor air temperature and relative humidity (RH) are in the range of 27–41 °C and 10–60%, respectively. The findings also revealed that by raising the RH of ambient air, the system will reach the maximum allowed RH faster and hence a smaller heat exchanger can be used when the ambient air has higher RH. Finally, performance of the DEC in a central province of Iran was investigated, and a design guideline was proposed to determine size of the required plate heat exchangers at various operating conditions.

scholarly journals Experimental performance comparison between circular and elliptical tubes in evaporative condensers

2021 ◽  
Author(s):  
Giuseppe Starace ◽  
Lorenzo Falcicchia ◽  
Pierpaolo Panico ◽  
Maria Fiorentino ◽  
Gianpiero Colangelo
Keyword(s):  
Heat Transfer ◽  
Experimental Approach ◽  
Fluid Dynamic ◽  
Major Axis ◽  
Performance Comparison ◽  
Operating Conditions ◽  
Condensation Temperature ◽  
Air Cooled Condensers ◽  
Reduced Scale ◽  
Dynamic Phenomena

AbstractIn refrigeration systems, evaporative condensers have two main advantages compared to other condensation heat exchangers: They operate at lower condensation temperature than traditional air-cooled condensers and require a lower quantity of water and pumping power compared to evaporative towers. The heat and mass transfer that occur on tube batteries are difficult to study. The aim of this work is to apply an experimental approach to investigate the performance of an evaporative condenser on a reduced scale by means of a test bench, consisting of a transparent duct with a rectangular test section in which electric heaters, inside elliptical pipes (major axis 32 mm, minor axis 23 mm), simulate the presence of the refrigerant during condensation. By keeping the water conditions fixed and constant, the operating conditions of the air and the inclination of the heat transfer geometry were varied, and this allowed to carry out a sensitivity analysis, depending on some of the main parameters that influence the thermo-fluid dynamic phenomena, as well as a performance comparison. The results showed that the heat transfer increases with the tube surface exposed directly to the air as a result of the increase in their inclination, that has been varied in the range 0–20°. For the investigated conditions, the average increase, resulting by the inclination, is 28%.

Hydrogen Production via Catalytic Autothermal Reforming of Desulfurized Jet-A Fuel

2016 ◽  
Author(s):  
Shuyang Zhang ◽  
Xiaoxin Wang ◽  
Peiwen Li
Keyword(s):  
Energy Efficiency ◽  
Hydrogen Production ◽  
Hydrogen Storage ◽  
Coke Formation ◽  
Autothermal Reforming ◽  
Operating Conditions ◽  
Hydrogen Yield ◽  
Fuel Conversion ◽  
Optimal Operating ◽  
Reaction Equilibrium

On-board hydrogen production via catalytic autothermal reforming is beneficial to vehicles using fuel cells because it eliminates the challenges of hydrogen storage. As the primary fuel for both civilian and military air flight application, Jet-A fuel (after desulfurization) was reformed for making hydrogen-rich fuels in this study using an in-house-made Rh/NiO/K-La-Ce-Al-OX ATR catalyst under various operating conditions. Based on the preliminary thermodynamic analysis of reaction equilibrium, important parameters such as ratios of H2O/C and O2/C were selected, in the range of 1.1–2.5 and 0.5–1.0, respectively. The optimal operating conditions were experimentally obtained at the reactor’s temperature of 696.2 °C, which gave H2O/C = 2.5 and O2/C = 0.5, and the obtained fuel conversion percentage, hydrogen yield (can be large than 1 from definition), and energy efficiency were 88.66%, 143.84%, and 64.74%, respectively. In addition, a discussion of the concentration variation of CO and CO2 at different H2O/C, as well as the analysis of fuel conversion profile, leads to the finding of effective approaches for suppression of coke formation.

Driveline Configuration and Terrain Effect on Slippage and Efficiency of a 6×6/6×4 Truck

2013 ◽  
Author(s):  
Vladimir V. Vantsevich ◽  
Dennis Murphy ◽  
Gianantonio Bortolin ◽  
Blair Farley ◽  
Gabriel Judd
Keyword(s):  
Energy Efficiency ◽  
Analytical Method ◽  
Power Distribution ◽  
Operating Conditions ◽  
Surface Type ◽  
Vehicle Efficiency ◽  
Terrain Effect ◽  
Truck Transportation

The power distribution between driving wheels has been shown to have a significant impact on vehicle energy efficiency, but there has only been limited research in this area. As shown in this paper, the wheel power distribution is largely dependent on the power dividing units (PDUs) which split/vector power between the driving wheels. The performance of a particular driveline system will also depend largely on the terrain conditions the vehicle encounters. This paper presents an analysis of PDU configurations in 6×6/6×4 terrain trucks. The vehicle efficiency is evaluated in a wide variety of typical operating conditions including varying surface types, speeds and accelerations, and slope conditions. An analytical method is presented which can be used to determine the tire circumferential forces and slippages. Finally, an analysis of the effects of the driveline configuration, terrain, and surface type on truck transportation efficiency is presented for three PDU combinations.

The Research of Marine Nuclear Power Two Loop Simulation Software Based on the Thermal System Analysis

2014 ◽  
Vol 983 ◽  
pp. 288-291
Author(s):  
Guo Lei Zhang ◽  
Xiang Dong Jin ◽  
Zhan Zhao ◽  
Zhi Jun Shi
Keyword(s):  
Nuclear Power ◽  
System Analysis ◽  
Simulation Analysis ◽  
Simulation Software ◽  
Operating Conditions ◽  
Two Phase ◽  
Design Data ◽  
Software Optimization ◽  
Power Simulation ◽  
Basic Functions

To study of Nuclear power simulation software's basic functions and mathematical model based on thermal analysis. Describes the two-phase flow model of GSE software superiority, as well as the software optimization program .Use of software tools for normal operating conditions of the simulation calculation and analysis of the results. Comparison with design data shows that,the software use in marine nuclear power two loop system simulation analysis field, the accuracy of it is higher.

scholarly journals Effect of transmembrane pressure control on energy efficiency during skim milk concentration by ultrafiltration at 10 and 50°C

2016 ◽  
Vol 99 (11) ◽  
pp. 8655-8664 ◽  
Author(s):  
S. Méthot-Hains ◽  
S. Benoit ◽  
C. Bouchard ◽  
A. Doyen ◽  
L. Bazinet ◽  
...  
Keyword(s):  
Energy Efficiency ◽  
Skim Milk ◽  
Pressure Control ◽  
Transmembrane Pressure

Powder Spheroidization Using Induction Plasma Technology

2000 ◽  
Author(s):  
N.M. Dignard ◽  
M.I. Boulos
Keyword(s):  
Energy Efficiency ◽  
Maximum Energy ◽  
Operating Conditions ◽  
Side Reactions ◽  
Induction Plasma ◽  
Silica Alumina ◽  
Change In The Mean ◽  
The Individual ◽  
Semi Empirical ◽  
Objective Being

Abstract An experimental study of the spheroidization efficiency of induction plasma processes was completed. The main objective being to obtain models which could be subsequently used for the prediction of the spheroidization efficiency for various powders and plasma operating conditions. Silica, alumina, chromium oxide and zirconia powders were treated during the experimentation. For the plasma treatment of the powders the installation used had a maximum available power of 50 kW with an operating frequency of 3 MHz. Operating conditions were varied such to minimize side reactions and the evaporation of powders. The resulting powders did show the presence of cavities and a slight change in the mean diameters. The maximum energy efficiency based semi-empirical model did predict the spheroidization efficiency of the particles beyond a defined critical point known as the maximum energy efficiency point. For the model, the maximum energy efficiency is distinct for the individual powders but remain within a defined range which is reflected in the small variations in the Z constant.

scholarly journals Effect of air combustion preheater on furnace efficiency by using refinery simulator

2021 ◽  
Vol 7 (3) ◽  
pp. 75-87
Author(s):  
Dr.Yosif J. Kadhem Almosawi ◽  
Warqaa A. Kadhem Alshimmary
Keyword(s):  
Crude Oil ◽  
Pressure Control ◽  
Operating Conditions ◽  
Oil Refining ◽  
Fuel Gas ◽  
Air Preheater ◽  
Heating Efficiency ◽  
Gas Consumption ◽  
The Right ◽  
Heating Up

One of the basic crude oil refining steps is the heat up to high temperature about 3700 C, which is done in the furnace. The balance between fuel and air required to combustion provide an economical and efficient heating. In this research operating data of heating up the furnace are collected by using an interactive simulator of Drilling System Company (ORTIS) which gives a flexibility of operation cannot be obtained in real furnace, these data are related to find the operation paths under different control system of manual, automatic and working automatic without pre-heating are used . Using of combustion air preheater, by exchanging heat with the flue gases, leading to increase furnace heating efficiency from 85% to 93% also the fuel supplied to the burners is more less than working without preheater. As the simulator used in this research very closed to real operating system of furnace which cover all the variables of furnace inside temperatures, excess air analyzer, and fuel gas control and inside pressure control. The using of interactive simulator is very useful in stating the right operating conditions. The use of pre-heating of combustion air is best economical method to reach heating the crude oil to the required temperature with minimum fuel gas consumption, which directly affects the efficiencies of the furnace in each case.

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.

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