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.

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.

Supersonic Flow Visualization Over Patented Rotors for a Novel Crypto-Steady Pressure Exchange Ejector Using Schlieren Photography

2009 ◽  
Author(s):  
Kartik V. Bulusu ◽  
Charles A. Garris
Keyword(s):  
Mechanical Energy ◽  
Helical Structure ◽  
High Energy ◽  
Two Fluids ◽  
Steady Pressure ◽  
Primary Fluid ◽  
Steady Mode ◽  
Schlieren Photography ◽  
Pressure Exchange ◽  
Secondary Fluid

The process of pressure exchange occurs where flows exchange mechanical energy through work of mutually exerted pressure forces at their interfaces. A novel ejector based on the concept of supersonic crypto-steady pressure exchange rather than the more energy dissipative turbulent entrainment phenomenon is being developed. To better understand the flow structures in context of the novel ejector, schlieren photography is being used as a flow visualizaton tool. The crypto-steady mode of pressure exchange can be achieved with rotors that enable the creating of psuedoblades and entrainment gullies by a primary supersonic fluid. The primary fluid can perform work on an entrained subsonic secondary fluid in a non-steady mode of fluid-fluid interaction. The primary fluid jets emanating from the rotor form a helical pattern whereby the secondary fluid becomes entrapped in the interstices of the helices. In the non-rotating case of the rotors, the voids between psuedoblades that create helical structure end up, providing entrainment gullies for the secondary fluid. In the rotating case, work is done by the expanding primary fluid on the secondary fluid by the pressure forces acting across the helical boundary between the two fluids. Crypto-steady pressure-exchange has the potential of providing society with a highly efficient means of compressing a low energy fluid through direct contact with a relatively high energy fluid, thereby circumventing the complexity and the energy dissipation associated with intervening machinery inherent in conventional compressors and turbulent mixing in ejectors. Global entropy can be calculated using steady inviscid two dimensional equations. The paper will report progress made by using schlieren photography on three patented rotors.

Computational Analysis of Flow Inside a Diffuser of Three-Dimensional Supersonic Non-Steady Ejectors

2005 ◽  
Author(s):  
Khaled Alhussan ◽  
Charles Garris
Keyword(s):  
Computational Analysis ◽  
Static Pressure ◽  
Three Dimensional ◽  
Critical Element ◽  
Induction Mechanism ◽  
Structure Of Flow ◽  
Primary Fluid ◽  
Contour Plots ◽  
Complex Fluid ◽  
Pressure Exchange

The work to be presented herein is a Computational Fluid Dynamics investigation of the complex fluid mechanisms that occur inside a non-steady, three-dimensional, supersonic pressure exchange ejector, specifically with regard to the pressure exchange mechanisms and the induction processes between a “driving” primary fluid and a “driven” secondary fluid and how this is affected by the diffuser surface. The results will show that this ejector is capable of producing the desire affect of the flow induction in a three-dimensional supersonic, non-steady, viscous flow. Results of contour plots of total pressure and static pressure demonstrate that the flow inside the diffuser is a critical element in flow induction mechanism, especially when a pressure recovery is needed. Results of velocity vectors will show the structure of flow induction mechanism in a complex three-dimensional conical surface.

Thermal Performance Comparison between Single and Double Storey Terrace Houses in Melaka, Malaysia

2016 ◽  
Vol 835 ◽  
pp. 416-422
Author(s):  
Fahanim Abdul Rashid ◽  
Asrul Mahjuddin Ressang Aminuddin ◽  
Norafida Ab. Ghaffar
Keyword(s):  
Relative Humidity ◽  
Thermal Comfort ◽  
Case Studies ◽  
Thermal Performance ◽  
High Energy ◽  
Performance Comparison ◽  
Building Envelope ◽  
The Difference ◽  
Economic Developments ◽  
Housing Typology

Over the past decade many studies were conducted to investigate the thermal performance of terraced houses in Malaysia. It was found that this housing typology failed to address the need for thermal comfort and alternatives to the narrow frontage with deep plan have been proposed with simulated good thermal performance. Although this is good progress for new generation of terraced houses, millions of units of terraced houses are still in use and new units with the outdated existing plans continued to get built due to consistently very high demand due to progressive urbanisation and rapid economic developments. Therefore, it is imperative that the thermal comfort issue for existing terraced houses is dealt with and through this paper a comparison between single and double storey terraced houses is made through analysis of indoor environmental monitoring (ambient temperature, relative humidity and air velocity) of two (2) selected case studies in Merlimau, Melaka. Contrary to popular belief, it is found that there is no statistical difference between both sets of indoor temperature and relative humidity between the case studies. This finding is indicative of the consistent and stable temporal temperature highs and lows in a 24 hour cycle despite the difference in indoor volume and distance between the ground floor and the roof cavity. Much of the reason is due to the materiality of the terraced houses construction and unsealed and uninsulated building envelope. Therefore, further research into improving the thermal performance of existing terraced houses of any typology have to be conducted to allow thermal comfort and to reduce reliance on high energy consuming air-conditioning.

scholarly journals Calculated and experimental evaluation heat pump distiller on pentane as working substance

2020 ◽  
Vol 324 ◽  
pp. 02007
Author(s):  
Gennady A. Ilyn ◽  
Ilya I. Malafeev ◽  
Vladimir B. Sapojnikov
Keyword(s):  
High Temperature ◽  
High Efficiency ◽  
Recovery Phase ◽  
High Energy ◽  
Heat Pumps ◽  
Working Fluid ◽  
Vapor Compression ◽  
The Cost ◽  
Reliable Methods ◽  
High Temperature Vapor

One of the most common and reliable methods of water treatment is the method of thermal distillation. Despite the reliability of the method, its application is constrained by high energy intensity. The most effective way to reduce the cost of production of distillate is the use of thermal transformers, providing regenerate and heat recovery phase transformations of the distillate. The use of working fluid with the most favorable thermodynamic properties is of paramount importance for the creation of high efficiency thermotransformers. The work is considered working fluid for high-temperature heat pumps and the results of the calculation-experimental study of high-temperature vapor compression heat-pumping distiller on natural working substance n-pentan.

Research on the thermal performance and storage life of series of high-energy hydrazine nitrate complexes

2017 ◽  
Vol 129 (3) ◽  
pp. 1887-1897 ◽  
Author(s):  
Guo-ying Zhang ◽  
Jian-chao Liu ◽  
Nai-meng Song ◽  
Ying Liu ◽  
Li Yang
Keyword(s):  
Thermal Performance ◽  
High Energy ◽  
Storage Life ◽  
Hydrazine Nitrate ◽  
And Storage ◽  
Nitrate Complexes

Simulations of Thermal Performance for One- and Two-Dimensional Insulation and Aluminum Foil Fire Barriers

2004 ◽  
Author(s):  
Mauricio A. Sa´nchez ◽  
William H. Sutton ◽  
Carlos A. Sa´nchez
Keyword(s):  
Heat Transfer ◽  
Numerical Model ◽  
Thermal Performance ◽  
Structural Integrity ◽  
High Energy ◽  
Ceramic Fiber ◽  
Discrete Ordinates ◽  
Two Dimensional ◽  
Barrier Materials ◽  
Fire Barrier

Nonbearing walls made of concrete frequently include one or two-dimensional gaps between sections to allow the concrete exert expansion or contraction due to temperature transients. These section gaps require the use of a thermal fire barrier to stop a fire from spreading during a period of time. In some applications, such as seismic structures, fire barriers are large and form substructures and partial enclosures. These type of fire barriers are often manufactured by layering alternating blankets of ceramic fiber insulation with bounding thin metallic foil sheets. In this case, the barrier must meet the specifications and effectiveness given by the ASTM standard E-119. This effectiveness is determined by the requirement of maintaining structural integrity by allowing some heat release while not permitting the fire flame to pass through. Little data is available on the thermal interaction of 2-D corners and splicing the layers for large barriers. It is expected that spatial and angular effects might either degrade performance or even cause “hot spots” in a barrier wall. Therefore, a numerical simulation of the barrier is accomplished by utilizing the spectral/gray and directional/modeled data of each one of the components and by taking into account two common geometrical building shapes. This simulation analysis is done by coupling of the discrete ordinates method in radiation heat transfer and the energy equation to previously published thermophysical experimental data used as a validation of the properties for fire barrier materials. Some of the effects of directional and surface properties and radiative heat transfer in fire barrier materials have been included in the numerical model. The Fluent®-based numerical model is able to match thermal performance of previous test systems. Initial calculations suggest that a fire barrier consisting of a 2D corner geometry exposed to a fire from either side would be thermally less robust than a slab of the same characteristic aspect ratio. This approximation has shown a preferential orientation for the barrier to be positioned when a fire or other high energy source is postulated.

scholarly journals Performance Analysis and Working Fluid Selection for Single and Two Stages Vapor Compression Refrigeration Cycles

Processes ◽  
2020 ◽  
Vol 8 (9) ◽  
pp. 1017
Author(s):  
Bahaa Saleh ◽  
Ayman A. Aly ◽  
Mishal Alsehli ◽  
Ashraf Elfasakhany ◽  
Mohamed M. Bassuoni
Keyword(s):  
Energy Efficiency ◽  
Environmental Impacts ◽  
High Energy ◽  
Working Fluid ◽  
Vapor Compression ◽  
Alternative Refrigerants ◽  
Two Stage ◽  
Azeotropic Mixtures ◽  
Vapor Compression Refrigeration ◽  
Two Stages

Screening for alternative refrigerants with high energy efficiency and low environmental impacts is one of the highest challenges of the refrigeration sector. This paper investigates the performance and refrigerant screening for single and two stages vapor compression refrigeration cycles. Several pure hydrocarbons, hydrofluorocarbons, hydrofluoroolefins, fluorinated ethers, and binary azeotropic mixtures are proposed as alternative refrigerants to substitute R22 and R134a due to their environmental impacts. The BACKONE equation of state is used to compute the thermodynamic properties of the candidates. The results show that the maximum coefficients of performance (COP) for single and two stage cycles using pure substances are achieved using cyclopentane with values of 4.14 and 4.35, respectively. On the other side, the maximum COP for the two cycles using azeotropic mixtures is accomplished using R134a + RE170 with values of 3.96 and 4.27, respectively. The two-stage cycle presents gain in COP between 5.1% and 19.6% compared with the single-stage cycle based on the used refrigerant. From the obtained results, among all investigated refrigerants, cyclopentane is the most suitable refrigerant for the two cycles from the viewpoint of energy efficiency. However, extra cautions should be taken due to its flammability.

scholarly journals Thermal Performance of Insulated Constructions—Experimental Studies

Buildings ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 49 ◽  
Author(s):  
Lars Gullbrekken ◽  
Steinar Grynning ◽  
Jørn Gaarder
Keyword(s):  
Thermal Performance ◽  
Experimental Studies ◽  
Energy Performance ◽  
High Energy ◽  
Mineral Wool ◽  
Wood Fibre ◽  
Nusselt Numbers ◽  
Performance Requirements ◽  
U Value ◽  
Passive Houses

Buildings that are designed to meet high-energy performance requirements, e.g., passive houses, require well-insulated building envelopes, with increased insulation thicknesses for roof, wall and floor structures. We investigate whether there are differences in the efficiency of thermal insulation materials at different moisture levels in the insulation and if there is a larger or smaller risk of natural convection in wood-fibre based insulation than in mineral wool. The work has mainly been performed by use of laboratory measurements included permeability properties and full-scale measurements of thermal transmittance of mineral wool and wood-fibre insulated constructions. In addition, calculations have been used to calculate resulting effects on the thermal performance of constructions. Results showed that the thermal conductivity was unaffected by moisture in the hygroscopic range. The air permeability was found to be approximately 50% higher for the wood-fibre insulation compared to mineral wool insulation. Measurements showed that the largest U-values and Nusselt numbers were found for the wall configuration. Calculation of the U-value of walls showed that in order to achieve the same U-value for the wood-fibre insulated wall as the mineral wool, it is necessary to add 20 mm insulation to the 250 mm wall and approximately 30 mm for the 400 mm wall.

scholarly journals Effect of Conical Strip Inserts and ZrO2/DI-Water Nanofluid on Heat Transfer Augmentation: An Experimental Study

Energies ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 4554
Author(s):  
Mohamed Iqbal Shajahan ◽  
Jee Joe Michael ◽  
M. Arulprakasajothi ◽  
Sivan Suresh ◽  
Emad Abouel Nasr ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Thermal Performance ◽  
Test Section ◽  
Volume Concentration ◽  
Swirl Flow ◽  
Performance Ratio ◽  
Transfer Rates ◽  
Heat Transfer Augmentation ◽  
Twist Ratio ◽  
Constant Wall Heat Flux

There is a significant enhancement of the heat transfer rate with the usage of nanofluid. This article describes a study of the combination of using nanofluid with inserts, which has proved itself in attaining higher benefits in a heat exchanger, such as the radiator in automobiles, industries, etc. Nanofluids are emerging as alternative fluids for heat transfer applications due to enhanced thermal properties. In this paper, the thermal hydraulic performance of ZrO2, awater-based nanofluid with various volume concentrations of 0.1%, 0.25%, and 0.5%, and staggered conical strip inserts with three different twist ratios of 2.5, 3.5, and 4.5 in forward and backward flow patterns were experimentally tested under a fully developed laminar flow regime of 0–50 lphthrough a horizontal test pipe section with a length of 1 m with a constant wall heat flux of 280 W as the input boundary condition. The temperatures at equidistant position and across the test section were measured using K-type thermocouples. The pressure drop across the test section was measured using a U-tube manometer. The observed results showed that the use of staggered conical strip inserts improved the heat transfer rates up to that of 130.5%, 102.7%, and 64.52% in the forward arrangement, and similarly 145.03%, 116.57%, and 80.92% in the backward arrangement with the twist ratios of 2.5, 3.5, and 4.5 at the 0.5% volume concentration of ZrO2 nanofluid. It was also seen that the improvement in heat transfer was comparatively lower for the other two volume concentrations considered in this study. The twist ratio generates more swirl flow, disrupting the thermal hydraulic boundary layer. Nanofluids with a higher volume concentration lead to higher heat transfer due to higher effective thermal conductivity of the prepared nanofluid. The thermal performance factor (TPF) with conical strip inserts at all volume concentrations of nanofluids was perceived as greater than 1. A sizable thermal performance ratio of 1.62 was obtained for the backward-arranged conical strip insert with 2.5 as the twist ratio and a volume concentration of 0.5% ZrO2/deionized water nanofluid. Correlations were developed for the Nusselt number and friction factor based on the obtained experimental data with the help of regression analysis.

Sign in / Sign up

Export Citation Format

Share Document