scholarly journals Feasibility Analysis of a Membrane Desorber Powered by Thermal Solar Energy for Absorption Cooling Systems

2020 ◽  
Vol 10 (3) ◽  
pp. 1110 ◽  
Author(s):  
Jonathan Ibarra-Bahena ◽  
Eduardo Venegas-Reyes ◽  
Yuridiana R. Galindo-Luna ◽  
Wilfrido Rivera ◽  
Rosenberg J. Romero ◽  
...  
Keyword(s):  
Experimental Data ◽  
Water Vapor ◽  
Solar System ◽  
Waste Heat ◽  
Cooling Water ◽  
Solution Temperature ◽  
Hydrophobic Membrane ◽  
Cooling Systems ◽  
Libr Solution ◽  
Absorption Cooling

In absorption cooling systems, the desorber is a component that separates the refrigerant fluid from the liquid working mixture, most commonly completed by boiling separation; however, the operation temperature of boiling desorbers is generally higher than the low-enthalpy energy, such as solar, geothermal, or waste heat. In this study, we used a hydrophobic membrane desorber to separate water vapor from an aqueous LiBr solution. Influencing factors, such as the H2O/LiBr solution and cooling water temperatures, were tested and analyzed. With the experimental data, a solar collector system was simulated on a larger scale, considering a 1 m2 membrane. The membrane desorber evaluation shows that the desorption rate of water vapor increased as the LiBr solution temperature increased and the cooling water temperature decreased. Based on the experimental data from the membrane desorber/condenser, a theoretical heat load was calculated to size a solar system. Meteorological data from Emiliano Zapata in Mexico were considered. According to the numerical result, nine solar collectors with a total area of 37.4 m2 provide a solar fraction of 0.797. The membrane desorber/condenser coupled to the solar system can provide an average of 16.8 kg/day of refrigerant fluid that can be used to produce a cooling effect in an absorption refrigerant system.

scholarly journals Cost and Performance Goals for Commercial Active Solar Absorption Cooling Systems

1985 ◽  
Vol 107 (2) ◽  
pp. 136-140 ◽  
Author(s):  
M. L. Warren ◽  
M. Wahlig
Keyword(s):  
Performance Analysis ◽  
Solar System ◽  
Thermal Performance ◽  
Return On Investment ◽  
Simulation Analysis ◽  
Cooling System ◽  
Cooling Systems ◽  
System Cost ◽  
Solar Cooling ◽  
Absorption Cooling

Economic and thermal performance analysis is used to determine cost goals for typical commercial active solar cooling systems to be installed between the years 1986 and 2000. Market penetration for heating, ventilating, and air conditioning systems depends on payback period, which is related to the expected return on investment. Postulating a market share for solar cooling systems increasing to 20 percent by the year 2000, payback and return on investment goals as a function of year of purchase are established. The incremental solar system cost goals must be equal to or less than the 20-year percent value of future energy savings, based on thermal performance analysis, at the desired return on investment. The methodology is applied to determine the allowable incremental solar system cost for commercial-scale, 25-ton absorption cooling systems based on the thermal performance predicted by recent simulation analysis, Methods for achieving these cost goals and expected solar cooling system costs will be discussed.

Performance of an Absorber With Hydrophobic Membrane Contactor at Aqueous Solution-Water Vapor Interface

2010 ◽  
Vol 2 (3) ◽  
Author(s):  
Ahmed Hamza H. Ali
Keyword(s):  
Aqueous Solution ◽  
Water Vapor ◽  
Water Temperature ◽  
Cooling Water ◽  
Cooling Capacity ◽  
Hot Water ◽  
Membrane Contactor ◽  
Water Coolant ◽  
Hydrophobic Membrane ◽  
Vapor Interface

In this study, a detailed modeling of the heat and mass transfer processes inside a plate-and-frame absorber with hydrophobic microporous membrane contactor at aqueous solution-water vapor interface as a part of a chiller model is developed. The absorber is a component of a 5 kW cooling capacity single effect lithium bromide-water absorption chiller with a hot water thermally driven generator, a water-cooled absorber, and a condenser. The model is used to investigate the performance of the absorber in case the chiller operates at different values of the inlet driving hot water and cooling water (coolant) temperatures. The results clearly indicate that for the same cooling capacity of the chiller and compared with the performance at the design point value, increasing the inlet driving hot water temperature results in an increase in the required absorber size and consequently a decrease in the absorber performance, while decreasing the cooling water (coolant) inlet temperature leads to slight decreases in the required absorber size and consequently an increase in the absorber performance. The effect is prominent and can be used to decrease the absorber size for chillers work in places where the option of lower inlet coolant temperature is available with normal driving hot water temperature.

Numerical Simulations of Heat and Mass Transfer in Condensing Heat Exchangers for Water Recovery in Power Plants

2011 ◽  
Author(s):  
Kwangkook Jeong ◽  
Harun Bilirgen ◽  
Edward Levy
Keyword(s):  
Experimental Data ◽  
Mass Transfer ◽  
Water Vapor ◽  
Sulfuric Acid ◽  
Heat Exchanger ◽  
Power Plant ◽  
Heat And Mass Transfer ◽  
Flue Gas ◽  
Cooling Water ◽  
Condensing Heat Exchanger

Power plants release a large amount of water vapor into the atmosphere through the stack. The flue gas can be a potential source for obtaining much needed cooling water for a power plant. If a power plant could recover and reuse a portion of this moisture, it could reduce its total cooling water intake requirement. One of the most practical way to recover water from flue gas is to use a condensing heat exchanger. The power plant could also recover latent heat due to condensation as well as sensible heat due to lowering the flue gas exit temperature. Additionally, harmful acids released from the stack can be reduced in a condensing heat exchanger by acid condensation. Condensation of vapors in flue gas is a complicated phenomenon since heat and mass transfer of water vapor and various acids simultaneously occur in the presence of non-condensable gases such as nitrogen and oxygen. Design of a condenser depends on the knowledge and understanding of the heat and mass transfer processes. A computer program for numerical simulations of water (H2O) and sulfuric acid (H2SO4) condensation in a flue gas condensing heat exchanger was developed using MATLAB. Governing equations based on mass and energy balances for the system were derived to predict variables such as flue gas exit temperature, cooling water outlet temperature, mole fraction and condensation rates of water and sulfuric acid vapors. The equations were solved using an iterative solution technique with calculations of heat and mass transfer coefficients and physical properties. An experimental study was carried out in order to yield data for validation of modeling results. Parametric studies for both modeling and experiments were performed to investigate the effects of parameters such as flue gas flow rate, cooling water flow rate, inlet cooling water temperature and tube configurations (bare and finned tubes) on condensation efficiency. Predicted results of water and sulfuric acid vapor condensation were compared with experimental data for model validation, and this showed agreement between experimental data and predictions to within a few percent. The most important parameters affecting performance of the condensing heat exchangers was the ratio of cooling water to flue gas flow rates, since this determines how much heat the cooling water can absorb. The computer program simultaneously calculates both water vapor condensation and sulfuric acid condensation in flue gas along downstream. Modeling results for prediction of sulfuric acid vapor concentration in the flue gas were compared with measured data obtained by the controlled condensation method. An analytical model of sulfuric acid condensation for oil-firing showed two trends — steep reduction within the high temperature heat exchanger and smooth reduction within lower temperature heat exchanger, which is in agreement with experimental data.

Absorption Characteristics of Thin Lithium Bromide (LiBr) Solution Film Constrained by a Porous Hydrophobic Membrane

2013 ◽  
Author(s):  
Rasool Nasr Isfahani ◽  
Saeed Moghaddam
Keyword(s):  
Water Vapor ◽  
Absorption Rate ◽  
Water Vapor Pressure ◽  
Lithium Bromide ◽  
Small Scale ◽  
Hydrophobic Membrane ◽  
Solution Flow ◽  
Libr Solution ◽  
Channel Thickness ◽  
Absorption Characteristics

An experimental study on absorption characteristics of water vapor into a thin lithium-bromide (LiBr) solution flow is presented. The LiBr solution flow is constrained between a superhydrophobic vapor-permeable wall and a solid surface that removes the heat of absorption. As opposed to conventional falling film absorbers, in this configuration, the solution film thickness and velocity can be controlled independently to enhance the absorption rate. The effects of water vapor pressure and cooling surface temperature on the absorption rate are studied. An absorption rate of approximately 0.005 kg/m2s was measured at a LiBr solution channel thickness and flow velocity of 160 μm and 4 mm/s, respectively. The absorption rate increased linearly with the water vapor driving potential at the tested solution channel thickness. The high absorption rate and the inherently compact form of the proposed absorber promise compact small-scale waste heat or solar-thermal driven cooling systems.

Experimental Study of Water Vapor Absorption Into Lithium Bromide (LiBr) Solution Constrained by Superhydrophobic Porous Membranes

2013 ◽  
Author(s):  
Rasool Nasr Isfahani ◽  
Saeed Moghaddam
Keyword(s):  
Experimental Study ◽  
Water Vapor ◽  
Absorption Rate ◽  
Waste Heat ◽  
Water Vapor Pressure ◽  
Lithium Bromide ◽  
Small Scale ◽  
Solution Flow ◽  
Libr Solution ◽  
Channel Thickness

An experimental study on absorption characteristics of water vapor into a thin lithium-bromide (LiBr) solution flow is presented. The LiBr solution flow is constrained between a superhydrophobic vapor-permeable wall and a solid surface that removes the heat of absorption. As opposed to conventional falling film absorbers, in this configuration, the solution film thickness and velocity can be controlled independently to enhance the absorption rate. The effects of water vapor pressure and cooling surface temperature on the absorption rate are studied. An absorption rate of approximately 0.005 kg/m2s was measured at a LiBr solution channel thickness and flow velocity of 160 μm and 4 mm/s, respectively. The absorption rate increased linearly with the water vapor driving potential at the tested solution channel thickness. The high absorption rate and the inherently compact form of the proposed absorber promise compact small-scale waste heat or solar-thermal driven cooling systems.

Performance of an Absorber With Hydrophobic Membrane Contactor at Aqueous Solution-Water Vapor Interface

2009 ◽  
Author(s):  
Ahmed Hamza H. Ali ◽  
Mahmoud Ahmed
Keyword(s):  
Aqueous Solution ◽  
Water Vapor ◽  
Lithium Bromide ◽  
Cooling Water ◽  
Hot Water ◽  
Inlet Temperature ◽  
Membrane Contactor ◽  
Water Coolant ◽  
Hydrophobic Membrane ◽  
Vapor Interface

In this study, analytical investigation at off-design conditions on performance of a plates-and-frames absorber with hydrophobic microporous membrane contactor at aqueous solution-water vapor interface are carried out. The absorber is a component of a single-effect lithium bromide-water absorption chiller with a hot water thermally driven generator and water-cooled absorber and condenser. Integrating the absorber model with the chiller model is used to evaluate the absorber performance at off-design conditions corresponding to different inlet both driving hot water and cooling water (coolant) temperatures. For the same cooling capacity of the chiller and referring to design point values, the results indicate that, increasing the inlet driving hot water temperature results in an increase in the required absorber size, consequently, a decrease in the absorber performance. While, decreasing the cooling water (coolant) inlet temperature leads to slightly decreases in the required absorber size, consequently, an increase in the absorber performance.

Rejection of Waste Heat From Power Plants Through Phased-Cooling

1975 ◽  
Vol 97 (1) ◽  
pp. 117-124
Author(s):  
J. A. MacFarlane ◽  
J. S. Goodling ◽  
G. Maples
Keyword(s):  
System Performance ◽  
Power Plants ◽  
Heat Dissipation ◽  
Waste Heat ◽  
Cooling Water ◽  
Meteorological Conditions ◽  
Optimum Number ◽  
Cooling Systems ◽  
Storage Pond ◽  
Power Plant Cooling

Because of the disadvantages associated with present power plant cooling systems, a new concept in waste heat dissipation, called “phased-cooling”, is introduced. Heated condenser cooling water is held in a storage pond during certain hours of the day, to be cooled at a later time by traveling across a cooling surface. A thermodynamic analysis of the system is performed, and the equations of heat transfer from a water surface are presented. The developed model is then used for prediction of system performance. The optimum number of storage hours is shown to be dependent upon the size of the system, the season, and meteorological conditions. Phased-cooling evaporation losses are approximately 40 percent less than those of cooling towers and cooling ponds. Condenser inlet temperatures are significantly lower than those of cooling ponds of similar size.

Assessment of thermal behavior of a cooling system to reduce thermal fatigue cracks in aluminum injection molds

2020 ◽  
pp. 75-86
Author(s):  
Sergio Antonio Camargo ◽  
Lauro Correa Romeiro ◽  
Carlos Alberto Mendes Moraes
Keyword(s):  
Thermal Fatigue ◽  
Cooling System ◽  
Fatigue Cracks ◽  
Cooling Water ◽  
Thermal Conditions ◽  
Thermal Gradients ◽  
Ansys Software ◽  
Cooling Systems ◽  
Thermal Fatigue Cracks ◽  
Number Of Cycles

The present article aimed to test changes in cooling water temperatures of males, present in aluminum injection molds, to reduce failures due to thermal fatigue. In order to carry out this work, cooling systems were studied, including their geometries, thermal gradients and the expected theoretical durability in relation to fatigue failure. The cooling system tests were developed with the aid of simulations in the ANSYS software and with fatigue calculations, using the method of Goodman. The study of the cooling system included its geometries, flow and temperature of this fluid. The results pointed to a significant increase in fatigue life of the mold component for the thermal conditions that were proposed, with a significant increase in the number of cycles, to happen failures due to thermal fatigue.

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