Energy Analysis of Single Effect Thermal Vapor Compression Desalination Process Based on Pressure Exchange Phenomenon

2009 ◽  
Author(s):  
Kaustubh A. Chabukswar ◽  
Charles A. Garris
Keyword(s):  
Energy Consumption ◽  
Flow Rate ◽  
Thermal Performance ◽  
Energy Analysis ◽  
Operating Conditions ◽  
Performance Ratio ◽  
Boiling Temperature ◽  
Vapor Compression ◽  
Single Effect ◽  
Pressure Exchange

A closed loop single effect thermal vapor compression desalination process is simulated based on pressure exchange phenomenon. Here the conventional ejector is replaced by a compressor-turbine device, where the high energy primary fluid expands over the turbine that drives the compressor through an ideal drive shaft. The compressor in turn compresses the low energy secondary fluid. Both the fluids are discharged at a constant pressure in a common mixing chamber where they undergo adiabatic mixing and then are discharged at an intermediate energy level. The functionality of the compressor-turbine device is similar to that of an ejector, hence this is also known as the turbomachinery analog of an ejector. The medium of energy transfer between the two fluids in case of compressor-expander device is pressure exchange. Energy analysis of the model is performed under various operating conditions. Key functional parameter like the boiling temperature, compression ratio, compressor-expander efficiencies and primary pressure are varied and its effect on the energy consumption per unit of distillate produced is examined. The system performance is evaluated based on the standard factors that affect the cost of the distillate like, thermal performance ratio, energy performance ratio and specific flow rate of cooling water. The model takes into consideration the inlet seawater conditions and its fouling effects as well as the use of superheated primary steam and its effects on performance of the system. With increase in the analog efficiency the energy consumption and thermal performance ratio improves steadily, where as it is observed that the flow rate of the distillate produced decreases. Initial results have shown performance ratios as high as 5.5 for ideal conditions at low primary pressures and low boiling temperature.

Analysis of Application of Pressure Exchange Device in Thermal Vapor Compression Desalination System

2009 ◽  
Author(s):  
Kaustubh A. Chabukswar ◽  
Charles A. Garris
Keyword(s):  
Thermal Performance ◽  
Compression Ratio ◽  
Production Cost ◽  
High Energy ◽  
Performance Ratio ◽  
Vapor Compression ◽  
Moving Interfaces ◽  
Primary Fluid ◽  
Mixing Chamber ◽  
Pressure Exchange

Recent advances in direct fluid-fluid flow induction provide potential for major improvement in performance of thermal distillation systems based on the pressure exchange phenomenon compared to the conventional turbulent mixing controlled ejectors. Pressure exchange devices utilize the work of nonsteady pressure forces acting across moving interfaces. Optimal performances of such devices can be determined through the use of the ideal turbomachinery analog. The analog is configured as a turbine-compressor unit, where the high energy primary fluid expands through the turbine that drives a compressor which compresses the low energy secondary fluid and the two then discharges in a common mixing chamber at a common intermediate pressure. The overall functioning of the turbomachinery analog is similar to the conventional ejector. Thus the turbomachinery analog provides the highest possible performance that an ejector can achieve ideally. An analytical single effect thermal vapor compression (TVC) desalination model is developed. The turbomachinery analog which is the simplest kind of pressure exchange device is simulated in place of the conventional ejector. The objective of the research is to investigate the performance of the system for various ejector efficiencies, so as to achieve the minimum production cost of distilled water. Such a development would make the process comparable with reverse osmosis and mechanical vapor compression desalination system. The system performance is expressed in the form of thermal performance ratio. For similar systems employing conventional steady-state ejectors, thermal performance ratios as high as 2 has been achieved for low compression ratio and low boiling temperature but at a price of high pressure primary steam. This paper reveals that the application of pressure exchange device can achieve even greater performance ratios for lower primary pressure and temperatures, contributing to a significant decrease in production cost. The model is designed for 5m3/day capacity, with an aim of achieving highest possible thermal efficiency. The system is analyzed by varying the critical operating parameters, like compression ratio, top brine temperature, primary pressure and ejector efficiency. The results show that with increase in primary pressure, the required primary temperature goes down. Also the application of pressure exchange device results in a phenomenal 3 fold rise in thermal performance ratio, as compared to conventional ejectors. The results achieved from the simulations are quite encouraging and promising for the future development of more efficient and compact device called the supersonic pressure exchange ejector.

scholarly journals Thermal Performance and Efficiency of a Mineral Oil Immersed Server Over Varied Environmental Operating Conditions

2017 ◽  
Vol 139 (4) ◽  
Author(s):  
Richard Eiland ◽  
John Edward Fernandes ◽  
Marianna Vallejo ◽  
Ashwin Siddarth ◽  
Dereje Agonafer ◽  
...  
Keyword(s):  
Flow Rate ◽  
Thermal Performance ◽  
Data Center ◽  
Mineral Oil ◽  
Operating Conditions ◽  
Published Data ◽  
Inlet Temperature ◽  
Air Cooling ◽  
Bulk Fluid ◽  
Oil Immersion

Complete immersion of servers in dielectric mineral oil has recently become a promising technique for minimizing cooling energy consumption in data centers. However, a lack of sufficient published data and long-term documentation of oil immersion cooling performance make most data center operators hesitant to apply these approaches to their mission critical facilities. In this study, a single server was fully submerged horizontally in mineral oil. Experiments were conducted to observe the effects of varying the volumetric flow rate and oil inlet temperature on thermal performance and power consumption of the server. Specifically, temperature measurements of the central processing units (CPUs), motherboard (MB) components, and bulk fluid were recorded at steady-state conditions. These results provide an initial bounding envelope of environmental conditions suitable for an oil immersion data center. Comparing with results from baseline tests performed with traditional air cooling, the technology shows a 34.4% reduction in the thermal resistance of the system. Overall, the cooling loop was able to achieve partial power usage effectiveness (pPUECooling) values as low as 1.03. This server level study provides a preview of possible facility energy savings by utilizing high temperature, low flow rate oil for cooling. A discussion on additional opportunities for optimization of information technology (IT) hardware and implementation of oil cooling is also included.

Optimization of Refrigeration Systems for High-Heat-Flux Microelectronics

2008 ◽  
Author(s):  
P. E. Phelan ◽  
Y. Gupta ◽  
H. Tyagi ◽  
R. Prasher ◽  
J. Cattano ◽  
...  
Keyword(s):  
Heat Flux ◽  
Energy Consumption ◽  
System Design ◽  
High Heat ◽  
Heat Fluxes ◽  
Operating Conditions ◽  
High Heat Flux ◽  
Vapor Compression ◽  
Refrigeration System ◽  
Compressor Inlet

Increasingly, military and civilian applications of electronics require extremely high heat fluxes, on the order of 1000 W/cm2. Thermal management solutions for these severe operating conditions are subject to a number of constraints, including energy consumption, controllability, and the volume or size of the package. Calculations indicate that the only possible approach to meeting this heat flux condition, while maintaining the chip temperature below 50 °C, is to utilize refrigeration. Here we report an initial optimization of the refrigeration system design. Because the outlet quality of the fluid leaving the evaporator must be held to approximately less than 20%, in order to avoid reaching critical heat flux, the refrigeration system design is dramatically different from typical configurations for household applications. In short, a simple vapor-compression cycle will require excessive energy consumption, largely because of the superheat required to return the refrigerant to its vapor state before the compressor inlet. A better design is determined to be a “two-loop” cycle, in which the vapor-compression loop is coupled thermally to a primary loop that directly cools the high-heat-flux chip.

Influence of operating conditions of milled peat jet transport on relative sliding of air and solid phases

2020 ◽  
pp. 57-60
Author(s):  
S. M. Petrenko ◽  
◽  
N. I. Berezovsky ◽  
Keyword(s):  
Energy Consumption ◽  
Flow Rate ◽  
Solid Phase ◽  
Operating Conditions ◽  
Solid Particles ◽  
Component Mixture ◽  
Mixture Flow ◽  
Milled Peat ◽  
Pipeline Route ◽  
Solid Phases

Air-and-peat mixture in horizontal jet transport pipeline is considered as a compressible two-component mixture with uniform distribution of solid peat particles in continuous air phase. Such heterogeneous medium flow is substituted for a flow of interpenetrating air phase and a quasi-solid phase approximating the flow of discrete particles. Such approach makes it possible to write individual equations of continuity and motion for each phase, but it is required to introduce the forces of aerodynamic interference at the phase boundaries in the motion equations. From the analysis of the known theoretical and experimental research data on jet transport of granular materials, it is possible to identify some parameters such that variation of any of these parameters changes the jet transport energy consumption. Such parameters are: jet capacity per mass of air and solid, Qair and Qs (kg/s) or input-output characteristic of mass concentration, μ = Qs/Qair; reduced velocities of air, Vair, solid particles, Vs, and soaring, Vsn, hereinafter called the flow-rate mode parameters, as well as the size and density of solid particles and the profile of the jet pipeline route. The flow-rate mode parameters are simply registered in the jet transport tests. The numerical determination procedure of the actual operating conditions of milled peat jet transport is justified. The known experimental data on jet transport of milled and treated peat are processed. It is found that the relative sliding ratio is functionally connected with all operating conditions in horizontal jet transport. The change of any parameter or their combination induces transition to air-and-peat mixture flow with various relative sliding of air and solid phases at different energy consumption of horizontal jet transport.

Thermal Performance Analysis of the Stationary Reflector/Tracking Absorber (SRTA) Solar Concentrator

1975 ◽  
Vol 97 (3) ◽  
pp. 451-456 ◽  
Author(s):  
J. F. Kreider
Keyword(s):  
Fluid Flow ◽  
High Temperature ◽  
Flow Rate ◽  
Thermal Performance ◽  
Concentration Ratio ◽  
Heat Energy ◽  
Operating Conditions ◽  
Fluid Flow Rate ◽  
Wide Range ◽  
Temperature Heat

The performance of a novel solar energy concentrating system consisting of a fixed, concave spherical mirror and a sun-tracking, cylindrical absorber is analyzed in detail. This concentrating system takes advantage of the spherical symmetry of the mirror and its linear image which, when taken together, form a tracking, solar-concentrating system in which only the small cylindrical absorber need move. The effects of mirror reflectance, concentration ratio, heat transfer fluid flow rate, radiative surface properties, incidence angle, an evacuated absorber envelope, and insolation level upon thermal performance of the concentrator are studied by means of a mathematical model. The simulation includes first order radiation and convection processes between the absorber and its concentric glass envelope and between the envelope and the environment; radiation processes are described by a dual-band, gray approximation. The energy equations are solved in finite difference form in order that heat flux and temperature distributions along the absorber may be computed accurately. The results of the study show that high-temperature heat energy can be collected efficiently over a wide range of useful operating conditions. The analysis indicates that mirror surface reflectance is the single most important of the principal governing parameters in determining system performance. Efficiency always increases with concentration ratio although the rate of increase is quite small for concentration ratios above 50. High fluid flow rate (i.e., lower operating temperature), an evacuated envelope, or a highly selective surface can enhance performance under some conditions. The conclusion of the study is that high-temperature heat energy can be generated at high efficiency by the present concentrator with present technology in sunny regions of the world.

Energy Efficiency of Refrigeration Systems for High-Heat-Flux Microelectronics

2010 ◽  
Vol 2 (3) ◽  
Author(s):  
P. E. Phelan ◽  
Y. Gupta ◽  
H. Tyagi ◽  
R. S. Prasher ◽  
J. Catano ◽  
...  
Keyword(s):  
Heat Flux ◽  
Energy Consumption ◽  
System Design ◽  
High Heat ◽  
Heat Fluxes ◽  
Operating Conditions ◽  
High Heat Flux ◽  
Vapor Compression ◽  
Refrigeration System ◽  
Compressor Inlet

Increasingly, military and civilian applications of electronics require extremely high-heat fluxes on the order of 1000 W/cm2. Thermal management solutions for these severe operating conditions are subject to a number of constraints, including energy consumption, controllability, and the volume or size of the package. Calculations indicate that the only possible approach to meeting this heat flux condition, while maintaining the chip temperature below 65°C, is to utilize refrigeration. Here, we report an initial thermodynamic optimization of the refrigeration system design. In order to hold the outlet quality of the fluid leaving the evaporator to less than approximately 20%, in order to avoid reaching critical heat flux, the refrigeration system design is dramatically different from typical configurations for household applications. In short, a simple vapor-compression cycle will require excessive energy consumption, largely because of the additional heat required to return the refrigerant to its vapor state before the compressor inlet. A better design is determined to be a “two-loop” cycle, in which the vapor-compression loop is coupled thermally to a pumped loop that directly cools the high-heat-flux chip.

scholarly journals Variable flow and optimization of chiller loading effect on energy saving for screw vapor compression-single effect absorption hybrid chiller plant in hospital mechanical room ‒ case study: Tehran heart hospital

2021 ◽  
Vol 22 ◽  
pp. 9
Author(s):  
Ronald Boghosian ◽  
Mostafa Mafi ◽  
Mohammad Hassan Panjeshahi ◽  
Abtin Ataei
Keyword(s):  
Energy Consumption ◽  
Energy Saving ◽  
Water Flow ◽  
Flow System ◽  
Vapor Compression ◽  
Absorption Chillers ◽  
Partial Load ◽  
Energy Consuming ◽  
Single Effect ◽  
Variable Water

Chiller plants are the most energy consuming system during summer season in residential, commercial and hospital buildings. The highly variable cooling demand of the buildings connected to a hybrid chiller plant included absorption and vapor compression chillers to achieve higher energy efficiencies is one of the important issues. Cooling load sharing strategies and apply the variable water flow system in chiller plant have a significant impact on energy consumption and consequently with more productivity and environmentally protected. This paper examines the behavior and pattern of energy consumption in a hybrid chiller plant that includes a combination of two air-cooled screw vapor compression and three single effect absorption chillers. In order to properly understand the pattern of energy consumption, an existing mechanical room in a hospital in Tehran has been studied for five months, and its energy consumption has been compared with the optimized model. The results indicate that the sequence of the chiller function and the way in which they are placed in the circuit during a partial load, is in highest importance in view point of energy saving also by Applying of variable water flow system for optimized chiller loading the more energy saving is achieved for hybrid absorption and vapor compression chiller plant.

scholarly journals Empirical Thermal Performance Investigation of a Compact Lithium Ion Battery Module under Forced Convection Cooling

2020 ◽  
Vol 10 (11) ◽  
pp. 3732
Author(s):  
Akinlabi A. A. Hakeem ◽  
Davut Solyali
Keyword(s):  
Flow Rate ◽  
Thermal Performance ◽  
Air Flow ◽  
Lithium Ion ◽  
Operating Conditions ◽  
Battery Pack ◽  
Performance Criteria ◽  
Maximum Temperature ◽  
Air Flow Rate ◽  
Worst Case

Lithium ion batteries (LiBs) are considered one of the most suitable power options for electric vehicle (EV) drivetrains, known for having low self-discharging properties which hence provide a long life-cycle operation. To obtain maximum power output from LiBs, it is necessary to critically monitor operating conditions which affect their performance and life span. This paper investigates the thermal performance of a battery thermal management system (BTMS) for a battery pack housing 100 NCR18650 lithium ion cells. Maximum cell temperature (Tmax) and maximum temperature difference (ΔTmax) between cells were the performance criteria for the battery pack. The battery pack is investigated for three levels of air flow rate combined with two current rate using a full factorial Design of Experiment (DoE) method. A worst case scenario of cell Tmax averaged at 36.1 °C was recorded during a 0.75 C charge experiment and 37.5 °C during a 0.75 C discharge under a 1.4 m/s flow rate. While a 54.28% reduction in ΔTmax between the cells was achieved by increasing the air flow rate in the 0.75 C charge experiment from 1.4 m/s to 3.4 m/s. Conclusively, increasing BTMS performance with increasing air flow rate was a common trend observed in the experimental data after analyzing various experiment results.

scholarly journals Evaluation of a Multiple-Effect Distillation Unit under Partial Load Operating Conditions

2013 ◽  
Vol 2013 ◽  
pp. 1-9
Author(s):  
Marios C. Georgiou ◽  
Aristides M. Bonanos ◽  
John G. Georgiadis
Keyword(s):  
Flow Rate ◽  
Dynamic Performance ◽  
Operating Conditions ◽  
Performance Ratio ◽  
Distillation Unit ◽  
Operating Modes ◽  
Multiple Effect ◽  
Partial Load ◽  
Multiple Effect Distillation ◽  
Flow Distributor

The design of a multiple-effect distillation (MED) system is presented, and the results for partial load operation of a single-effect distillation unit are presented. The MED is designed to be driven by solar energy, and thus the dynamic performance and partial load operation production are of interest. Two operating modes are considered in the analysis, with and without the use of a flow distributor. Various tests were performed varying the heating steam flow rate and the intake seawater flow rate. Results are presented as a function of the performance ratio, representing the amount of distillate produced per unit mass of steam input. Results indicate that a higher performance is obtained with the use of the flow distributor.

scholarly journals Assessing the Impact of Operating Conditions on the Energy and Exergy Efficiency for Multi-Effect Vacuum Membrane Distillation Systems

Water ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1500
Author(s):  
A. Najib ◽  
J. Orfi ◽  
H. Alansary ◽  
E. Ali
Keyword(s):  
Energy Consumption ◽  
Pilot Plant ◽  
Membrane Distillation ◽  
Exergy Efficiency ◽  
Operating Conditions ◽  
Performance Ratio ◽  
Cold Temperatures ◽  
Energy And Exergy ◽  
Vacuum Membrane Distillation ◽  
The Impact

A comprehensive study was conducted to elucidate the effect of operating conditions on the performance of a multi-effect vacuum membrane distillation pilot plant. A theoretical assessment of the energy and exergy efficiency of the process was achieved using a mathematical model based on heat and mass transfer, which was calibrated using experimental data obtained from the pilot plant. The pilot plant was a solar vacuum multi-effect membrane distillation (V-MEMD) module comprising five stages. It was found that a maximal permeate mass flux of 17.2 kg/m2·h, a recovery ratio of 47.6%, and a performance ratio of 5.38% may be achieved. The resulting gain output ratio (GOR) under these conditions was 5.05, which is comparable to previously reported values. Furthermore, the present work systematically evaluated not only the specific thermal energy consumption (STEC), but also the specific electrical energy consumption (SEEC), which has been generally neglected in previous studies. We show that STEC and SEEC may reach 166 kWh/m3 and 4.5 kWh/m3, respectively. We also observed that increasing the feed flow rate has a positive impact on the process performance, particularly when the feed temperature is higher than 65 °C. Under ideal operational conditions, the exergetic efficiency reached 21.1%, and the maximum fraction of exergy destruction was localized in the condenser compartment. Variation of the inlet hot and cold temperatures at a constant differential showed an interesting and variable impact on the performance indicators of the V-MEMD unit. The difference with the lowest inlet temperatures exhibited the most negative impact on the system performance.

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