A Liquid Desiccant System for Solar Cooling and Dehumidification

2004 ◽  
Vol 126 (3) ◽  
pp. 879-885 ◽  
Author(s):  
K. Gommed ◽  
G. Grossman
Keyword(s):  
Direct Contact ◽  
Cooling System ◽  
Low Cost ◽  
Cooling Water ◽  
Ambient Air ◽  
Low Grade ◽  
Liquid Desiccant ◽  
Flow Rates ◽  
Heating And Cooling ◽  
Air Stream

The growing demand for air conditioning, particularly in hot and humid climates has caused a significant increase in demand for energy resources. A promising solar technology with potential to alleviate the problem is an open absorption system, where humidity is absorbed directly from the air to be treated by direct contact with the absorbent. The absorbent is then regenerated, again in direct contact with an external air stream, at relatively low temperatures of the heat source. The paper describes a study of a liquid desiccant cooling system designed to air-condition a group of offices on the top floor of a building in the Mediterranean city of Haifa, Israel. The system is capable of using as its source of power low-grade solar heat, of the type obtainable from low-cost flat plate collectors, and has a potential to provide both cooling and dehumidification in variable ratios, as required by the load. Several cycle variations have been considered, corresponding to different design options. A parametric study shows that entrance conditions of the ambient air significantly affect the heat and mass transfer occurring during the dehumidification process. The temperatures and flow rates of the heating and cooling water and the flow rates of solution through the dehumidifier and regenerator affect the humidity of the supply air delivered to the conditioned space, and show an optimum in certain cases.

Hydraulic model of a water cooling system in a chemical plant

1988 ◽  
Vol 53 (4) ◽  
pp. 788-806
Author(s):  
Miloslav Hošťálek ◽  
Jiří Výborný ◽  
František Madron
Keyword(s):  
Flow Rate ◽  
Cooling System ◽  
Cooling Water ◽  
Graph Algorithm ◽  
Automatic Generation ◽  
Hydraulic Calculation ◽  
Return Flow ◽  
Flow Rates ◽  
Pressure Losses ◽  
Controlled Flow

Steady state hydraulic calculation has been described of an extensive pipeline network based on a new graph algorithm for setting up and decomposition of balance equations of the model. The parameters of the model are characteristics of individual sections of the network (pumps, pipes, and heat exchangers with armatures). In case of sections with controlled flow rate (variable characteristic), or sections with measured flow rate, the flow rates are direct inputs. The interactions of the network with the surroundings are accounted for by appropriate sources and sinks of individual nodes. The result of the calculation is the knowledge of all flow rates and pressure losses in the network. Automatic generation of the model equations utilizes an efficient (vector) fixing of the network topology and predominantly logical, not numerical operations based on the graph theory. The calculation proper utilizes a modification of the model by the method of linearization of characteristics, while the properties of the modified set of equations permit further decrease of the requirements on the computer. The described approach is suitable for the solution of practical problems even on lower category personal computers. The calculations are illustrated on an example of a simple network with uncontrolled and controlled flow rates of cooling water while one of the sections of the network is also a gravitational return flow of the cooling water.

scholarly journals Analysis of the evaporative towers cooling system of a coal-fired power plant

2012 ◽  
Vol 16 (suppl. 2) ◽  
pp. 375-385 ◽  
Author(s):  
Mirjana Lakovic ◽  
Slobodan Lakovic ◽  
Milos Banjac
Keyword(s):  
Energy Efficiency ◽  
Power Plant ◽  
Theoretical Analysis ◽  
Power Plants ◽  
Cooling Tower ◽  
Cooling System ◽  
Low Cost ◽  
Cooling Water ◽  
Energy Efficiency Improvement ◽  
Condensing Pressure

The paper presents a theoretical analysis of the cooling system of a 110 MW coal-fired power plant located in central Serbia, where eight evaporative towers cool down the plant. An updated research on the evaporative tower cooling system has been carried out to show the theoretical analysis of the tower heat and mass balance, taking into account the sensible and latent heat exchanged during the processes which occur inside these towers. Power plants which are using wet cooling towers for cooling condenser cooling water have higher design temperature of cooling water, thus the designed condensing pressure is higher compared to plants with a once-through cooling system. Daily and seasonal changes further deteriorate energy efficiency of these plants, so it can be concluded that these plants have up to 5% less efficiency compared to systems with once-through cooling. The whole analysis permitted to evaluate the optimal conditions, as far as the operation of the towers is concerned, and to suggest an improvement of the plant. Since plant energy efficiency improvement has become a quite common issue today, the evaluation of the cooling system operation was conducted under the hypothesis of an increase in the plant overall energy efficiency due to low cost improvement in cooling tower system.

Structure Optimization Design about the Wet Grinding Sanding Machine with Double Cooling System

2014 ◽  
Vol 685 ◽  
pp. 208-211
Author(s):  
Shi Yang Wei ◽  
Guang Zhen Cheng ◽  
Zhe Tong ◽  
Jia Hang Ma ◽  
Yan Chun Gu ◽  
...  
Keyword(s):  
Optimization Design ◽  
Material Handling ◽  
Bending Strength ◽  
Cooling System ◽  
Low Cost ◽  
Water Channel ◽  
Cooling Water ◽  
Cylinder Liner ◽  
Wet Grinding ◽  
Working Volume

This paper introduced a wet grinding sanding machine, it is used for fine material. The machine was consists of three parts by stirring grated agencies, cooling system, material handling systems. Rotor and its Rod pin using the whole cast structure, low cost, conical rod pin to improve bending strength. Annular space between the cylinder and the cylinder liner formed cylinder cooling water channel, it connected respectively inlet and return pipes. Hollow spindle, inner pipe, pipe joint and rotor cavity form rotor cooling water channel, dual cooling effect is good. Shell fixed to the cylinder, turn the handle nut, interaction between the thread and the external thread on the piston, forces the pistons to axial movement, used to adjust the working volume and pressure of sanding machine.

scholarly journals A Transient Method for Determining Thermal Diffusivity of Tobacco Stems

1989 ◽  
Vol 14 (5) ◽  
pp. 321-326
Author(s):  
NN Barthakur ◽  
NP Arnold
Keyword(s):  
Thermal Diffusivity ◽  
Cooling Curves ◽  
Microwave Generator ◽  
Unsteady State ◽  
Transient Method ◽  
Flow Rates ◽  
Heating And Cooling ◽  
Air Stream ◽  
Stem Temperature

AbstractA microwave generator and a closed-circuit wind tunnel were used to measure the thermal diffusivity of tobacco (Nicotianatabacum L.) stems in vivo by the unsteady-state method. A simple mathematical model for heat flow, based on Fourier's heat-conduction equation and Newton's law of cooling, was used in this study. The microwave method was found to be relatively rapid as both heating and cooling of a cylindrical stem in an air stream could be completed in approximately 30 minutes for thermal-diffusivity determinations. Thermal-diffusivity value of the tobacco stems, containing 94 % moisture and a mean stem temperature of 30°C, was found to be (1.38 ± 0.06) × 10-7 m2 s-1. The coefficient of variation for the measurements did not exceed 1.4 % as determined through the analysis of cooling curves for five different air-flow rates over the stems. This study showed that the microwave technique could be effectively used to determine both accurately and reliably the thermal diffusivity of tobacco stems in vivo.

Research on Ratio Selection of Mixed LiBr-CaCl2 Solution for Liquid Desiccant Cooling System

2014 ◽  
Vol 525 ◽  
pp. 598-602 ◽  
Author(s):  
Xiao Zhao ◽  
Xiu Wei Li ◽  
Fang Wang
Keyword(s):  
Cooling System ◽  
Working Environment ◽  
Low Grade ◽  
Mixed Solution ◽  
Mixing Ratio ◽  
Liquid Desiccant ◽  
Local Composition ◽  
Ideal Mixing ◽  
Libr Solution ◽  
Low Grade Heat

In recent years, liquid desiccant cooling system has shown its potential research value for its low-grade heat using and energy-saving. Thermal properties of liquid desiccant, especially its vapor pressure greatly affects the dehumidification efficiency of this system. Here comes the problem to find a liquid desiccant with better dehumidification effect and lower cost. To solve this problem, a local composition model: nonrandom two-liquid (NRTL) theory could be used to calculate a mixed solution of LiBr-CaCl2, and calculates the ideal mixing ratio of this solution in a working environment. The best mixing ratio with cost-effectiveness can be worked out by taking into account the initial cost of the solution. Study shows that: compared to single LiBr solution, the dehumidification effect could be raised by more than 8.2% and the costs could be reduced by 20% with mixed LiBr-CaCl2 solution.

Research and Application of Dynamic Secondary Cooling Control System for a Continuous Steel Billet Caster

2012 ◽  
Vol 572 ◽  
pp. 404-409
Author(s):  
Zun Peng ◽  
Wen Hao Hu ◽  
Yan Ping Bao ◽  
Min Wang ◽  
Li Qiang Zhang ◽  
...  
Keyword(s):  
Water Flow ◽  
Cooling System ◽  
Continuous Casting Machine ◽  
Casting Machine ◽  
Cooling Water ◽  
Transfer Model ◽  
Secondary Cooling ◽  
Billet Temperature ◽  
Flow Rates ◽  
Billet Caster

A two-dimensional heat-transfer model for transient simulation of a billets caster is presented. Its accuracy is verified through measured billet temperature and shell thickness. Billets temperature and solidification are computed by this model as a function of time varying casting speed, secondary cooling water flow rates and temperature, billet cross section, steel grade, and pouring and ambient temperatures. A control methodology and algorithm suitable for online control of 5 strands billet continuous casting machine is integrated in this model. The ability of this model to control the surface temperature profile is demonstrated through dynamic and precise adjustment of secondary cooling water flow rates. This secondary cooling system has been applied to a billet caster in Hangzhou Steel Corporation.

Ground Cooling System for Improving the Efficiency of Low Temperature Power Generation

2014 ◽  
Author(s):  
Rachana Vidhi ◽  
Pardeep Garg ◽  
Matthew S. Orosz ◽  
D. Yogi Goswami ◽  
Pramod Kumar
Keyword(s):  
Power Generation ◽  
Heat Exchanger ◽  
Las Vegas ◽  
Cooling System ◽  
Cooling Water ◽  
Organic Rankine Cycle ◽  
Ambient Air ◽  
The United States ◽  
Buried Pipe ◽  
Working Fluids

This paper presents an analysis of an organic Rankine cycle (ORC) with dry cooling system aided by an earth-coupled passive cooling system. Several organic fluids were considered as working fluids in the ORC in the temperature range of 125–200°C. An earth-air-heat-exchanger (EAHE) is studied for a location in the United States (Las Vegas) and another in India (New Delhi), to pre cool the ambient air before entering an air-cooled condenser (ACC). It was observed that the efficiency of the system improved by 1–3% for the system located in Las Vegas and fluctuations associated with temperature variations of the ambient air were also reduced when the EAHE system was used. A ground-coupled heat pump (GCHP) is also studied for these locations where cooling water is pre cooled in an underground buried pipe before entering a condenser heat exchanger in a closed loop. The area of the buried pipe and the condenser size are calculated per kW of power generation for various working fluids.

Analysis of a Solar Space Cooling System Using Liquid Desiccants

1990 ◽  
Vol 112 (4) ◽  
pp. 246-250 ◽  
Author(s):  
P. Gandhidasan
Keyword(s):  
Heat Exchanger ◽  
Cooling System ◽  
Cooling Water ◽  
Ambient Air ◽  
Solution Concentration ◽  
Simple Expression ◽  
Ventilation Mode ◽  
Cooling Water Temperature ◽  
System A ◽  
Space Cooling

For tropical countries, solar space cooling is an attractive proposition. Dehumidification of air in hot, humid climates is almost as important as cooling. Removal of moisture from the air is much easier to achieve than cooling the air. The proposed cooling system operates on the ventilation mode. The ambient air is dehumidified using liquid desiccants followed by adiabatic evaporative cooling. The desiccant soon becomes saturated with the water extracted from the air and can be regenerated by using solar energy. For this system, a simple expression is derived in this paper to predict the amount of heat removed from the space to be conditioned in terms of known initial parameters through a simplified vapor pressure correlation and effectiveness of the dehumidifier and the heat exchanger. The effect of ambient air conditions, solution concentration, the cooling water temperature and the effectiveness of the dehumidifier and the heat exchanger on the performance of the cooling system are also discussed in this paper.

Fault Diagnosis Technique for a Squirrel Cage Fan Using Vibration Analysis Signals

2014 ◽  
Author(s):  
Laura Delgado ◽  
Jose Gonzalez Perez ◽  
Jesus M. Fernandez Oro ◽  
Sandra Velarde-Suárez ◽  
David Rodríguez ◽  
...  
Keyword(s):  
Fault Diagnosis ◽  
Low Cost ◽  
Fast Response ◽  
Rotor Blades ◽  
Centrifugal Fan ◽  
Flow Rates ◽  
Heating And Cooling ◽  
Squirrel Cage ◽  
Geometrical Constraints ◽  
Diagnosis Technique

An experimental vibration study for a small centrifugal fan unit is presented in this work. The flow features in this kind of units are always of unsteady nature due to the geometrical constraints. As a consequence of such unsteady features, the vibrations and noise become often a serious design problem and may cause the unit bad functioning. With the use of fast response accelerometers, a fault diagnosis protocol is introduced in order to measure the extent of signal variations for different and expected failures. The study is based on the experimental measurements of two perpendicularly placed sensors which capture the acceleration signals for three different flow rates and three different operations, namely, the normal (or no failure) operation, the obstructed channel operation and the unbalance shaft operation. A squirrel cage or Sirocco fan is used for the study. It is a kind of centrifugal turbomachine with forward curved blades, often characterized by their small size. Its low cost and size make them be ideal for residential heating and cooling of vehicles. One of the important characteristics, the small chord of the rotor blades and the high number of them often used has been previously reported in the bibliography. Typically, most common damages or faults come from the moving blades, bearings, fixed blades, rotor and sealing. In general, the vibration signals indicate malfunction symptoms, one symptom may be due to two different faults, and the same fault can produce two different symptoms. The main goal of the study is the application of a fault diagnosis technique as the purified orbit diagram (POD) to reveal the limit range values for some standard failures. The finding of such limits is determinant to implement a fault diagnosis protocol that will decrease the maintenance costs and increase the operation efficiency of the unit. Such protocol would become straightforward from the presented data. The Purified Orbit Diagram is obtained by harmonic reconstructing corresponding harmonic components of two perpendicular directions in time domain. Three different flow rates, namely nominal and two off-design conditions are tested to be able to compare the different POD components as a function of the flow rate.

Research Progress of Liquid Desiccant Evaporative Cooling Air Conditioning System

2013 ◽  
Vol 732-733 ◽  
pp. 531-536
Author(s):  
Tong Hua Zou ◽  
Min Wang ◽  
Sai Feng Deng ◽  
Yong Li
Keyword(s):  
Air Conditioning ◽  
Cooling System ◽  
Evaporative Cooling ◽  
Research Progress ◽  
Low Grade ◽  
Liquid Desiccant ◽  
Air Conditioning System ◽  
Evaporative Cooling System ◽  
Cooling Technology ◽  
Cooling Air

Evaporative cooling technology is a refrigeration technology by water evaporating endothermic, with zero-pollution, environmental-friendly, energy saving, and other advantages, which makes it widely used. Nevertheless, due to its working characteristic, the application of evaporative cooling technology is limited, particularly in some areas with high humidity. Using the liquid desiccant dehumidification and evaporative cooling technology leads to a solution, named liquid desiccant evaporative cooling air conditioning system extends the application of evaporative cooling technology. This article on liquid desiccant evaporative cooling system provides a brief overview about research status, full usage of the low grade thermal energy, the practical application and new development of the system.

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