Steady-State Performance of a Prototype (200 cfm) Liquid-to-Air Membrane Energy Exchanger (LAMEE) Under Summer and Winter Test Conditions

2013 ◽  
Author(s):  
Davood Ghadiri Moghaddam ◽  
Gazi Mahmood ◽  
Gaoming Ge ◽  
John Bolster ◽  
Robert W. Besant ◽  
...  
Keyword(s):  
Steady State ◽  
Salt Solution ◽  
Air Conditioning ◽  
Winter Conditions ◽  
Test Conditions ◽  
Membrane Energy ◽  
Air Conditioning Systems ◽  
New Generation ◽  
Heat And Moisture ◽  
Steady State Performance

Liquid-to-air membrane energy exchangers (LAMEEs) are a new generation of energy exchangers in air-conditioning systems to transfer both heat and moisture. In this paper, the performance of a 200 cfm LAMEE is numerically and experimentally investigated under summer and winter test conditions when Lithium Chloride (LiCl) is used as a salt solution in the exchanger. The results show that the LAMEE has almost the same total effectiveness at summer and winter conditions, but the latent effectiveness of the LAMEE is higher at the summer conditions. Also, the agreement between the experimental and numerical results is acceptable for all the tests, and they are within their uncertainty ranges except for the latent effectiveness of the LAMEE tested under winter test conditions.

scholarly journals Dehumidification performance investigation of run-around membrane energy exchanger system

2016 ◽  
Vol 20 (6) ◽  
pp. 1927-1938 ◽  
Author(s):  
Miklos Kassai ◽  
Gaoming Ge ◽  
Carey Simonson
Keyword(s):  
Salt Solution ◽  
Moisture Transfer ◽  
Heat And Moisture Transfer ◽  
Solution Flow ◽  
Permeable Membrane ◽  
Air Temperatures ◽  
Air Stream ◽  
Membrane Energy ◽  
Air Conditioning Systems ◽  
Heat And Moisture

Liquid-to-air membrane energy exchanger is a novel membrane base energy exchanger, which allows both heat and moisture transfer between air and a salt solution. It uses semi-permeable membrane to eliminate entrainment of liquid desiccant as aerosols in air stream and allow simultaneous heat and moisture transfer between salt solution flow and airflow. The heat and mass transfer performance of a single liquid-to-air membrane energy exchanger is significantly dependent on two dimensionless parameters. They are the number of heat transfer units (NTU) and the ratio of heat capacity rates between solution flow and air flow (Cr*). The liquid-to-air membrane energy exchangers can also be applied in a run-around membrane energy exchanger system, which is mainly comprised of two liquid-to-air membrane energy exchangers and a closed loop of aqueous desiccant solution and used as a passive energy recovery system to recover the energy (both heat and moisture) from the exhaust air to precondition the supply air in air conditioning systems. In this study the dehumidification capacity of a run-around membrane energy exchanger is investigated numerically at different exhaust air temperatures and Cr* values. Increasing the exhaust air temperature or the Cr* would enhance the dehumidification capacity of the a run-around membrane energy exchanger system under Cr*?1, but the improvement is limited. The dehumidification capacity at low Cr* is much lower than that under the optimal Cr* value (Cr*=3.2) where the maximum latent effectiveness is obtained.

Steady-State Performance of a Small-Scale Liquid-to-Air Membrane Energy Exchanger for Different Heat and Mass Transfer Directions, and Liquid Desiccant Types and Concentrations: Experimental and Numerical Data

2013 ◽  
Vol 135 (12) ◽  
Author(s):  
Davood Ghadiri Moghaddam ◽  
Philip LePoudre ◽  
Robert W. Besant ◽  
Carey J. Simonson
Keyword(s):  
Experimental Data ◽  
Mass Transfer ◽  
Steady State ◽  
Heat And Mass Transfer ◽  
Salt Solution ◽  
Test Facility ◽  
Small Scale ◽  
Air Cooling ◽  
Test Cases ◽  
Membrane Energy

A liquid-to-air membrane energy exchanger (LAMEE) is an energy exchanger that allows heat and moisture transfer between air and salt solution flows through a semipermeable membrane. For the first time, a novel small-scale single-panel LAMEE test facility is used to experimentally investigate the effect of the direction of heat and mass transfers for the air and salt solution flows, and the effect of different salt solution types and concentrations on the LAMEE effectiveness. The data for steady-state effectiveness of the LAMEE are compared to the simulation results of a numerical model. Two studies are conducted; first a study based on different heat and mass transfer directions (four test cases), and second a study focused on the influence of solution types and concentration on LAMEE performance. For the first study, NTU = 3 and four different heat capacity ratios (i.e., Cr* = 1, 3, 5, 7) are used, with a LiCl salt solution in the exchanger. Mass and energy balances for all the test cases and the repeatability of the experimental data for the air cooling and dehumidifying test case show that the experimental data are repeatable and within an acceptable uncertainty range. The results show increasing effectiveness with increasing Cr*, and good agreement between the numerical and experimental results for both air cooling and dehumidifying and air heating and humidifying test cases. In the second study, two different salt solutions (i.e., LiCl and MgCl2), and three different concentrations for the LiCl solution (i.e., 25%, 30%, and 35%) are selected to investigate the effect of different salt solution types and concentrations on the performance of the LAMEE. A maximum difference of 10% is obtained for the LAMEE total effectiveness data with the different salt solution types and concentrations. The results show that both the salt solution type and concentration affect the LAMEE effectiveness, and changing the concentration is one way to control the supply air outlet humidity ratio.

scholarly journals Assessing the Environmental Impact of Thermal Transmittance Tests Performed in Façades of Existing Buildings: The Case of Spain

2020 ◽  
Vol 12 (15) ◽  
pp. 6247
Author(s):  
David Bienvenido-Huertas
Keyword(s):  
Energy Consumption ◽  
Environmental Impact ◽  
Thermal Gradient ◽  
Air Conditioning ◽  
Experimental Methods ◽  
Existing Buildings ◽  
Heating Systems ◽  
Thermal Transmittance ◽  
Test Conditions ◽  
Air Conditioning Systems

Thermal transmittance tests constitute an appropriate tool to assess the energy performance of existing buildings. The heat flow meter method and the thermometric method are the most used experimental methods. One of the main criteria to guarantee appropriate test conditions and the representation of results is to ensure a high thermal gradient. For this purpose, heating or air conditioning systems should be used from three to seven days. Most studies related to experimental methods have addressed the appropriate test conditions; however, the environmental impact related to these conditions have not been analyzed. This study analyzes the energy consumption and the CO2 emissions related to the conditions of the thermal gradient required for tests. An energy analysis of 129,600 cases located in Spain was conducted. The results showed that heating systems are the best option to perform thermal transmittance tests, whereas air conditioning systems do not guarantee appropriate test conditions. As for the energy consumption and the percentage of hours with an appropriate thermal gradient, the adequacy of the heating setpoint temperature according to the predicted estimations of the external temperature during tests would mitigate their environmental impact. The reason is that, in certain cases, the increase of the setpoint temperature does not improve test conditions. Also, the use of heating systems would imply short test durations. Finally, the selection of small rooms with a small façade length would reduce the percentage of CO2 emissions between 31.37% and 36.1%. The results of this study could guarantee a more sustainable performance of thermal transmittance tests. In addition, the results could be used to perform life cycle analysis on buildings where thermal transmittance tests are performed.

Steady-State Hydrodynamic and Thermal Interactions Between Secondary User-Loops in a Hydraulic Network

2005 ◽  
Author(s):  
Walfre Franco ◽  
Weihua Cai ◽  
Mihir Sen ◽  
K. T. Yang
Keyword(s):  
Steady State ◽  
Air Conditioning ◽  
Hydrodynamic Interaction ◽  
Secondary User ◽  
The Other ◽  
Flow Rates ◽  
Fundamental Part ◽  
Hydraulic Network ◽  
Air Conditioning Systems ◽  
Cooling Loop

Hydraulic networks constitute a fundamental part of heating, ventilating and air conditioning systems in buildings and high rises. In order to optimize large and complex networks it is important to understand the effects of operational changes in one loop on the others. The objective of this study is to investigate the time-independent flow and thermal interactions between secondary user-loops, in a hydraulic network that is used for cooling, when the system goes from one steady state to another. The study is experimental and was carried out on a facility which has a primary cooling loop, three secondary loops, and a primary heating loop. The flow was abruptly changed by actuating a valve in one of the loops causing changes in the other two loops. Results show that the change of flow rates and pressure differences in the other two loops are linearly dependent on that in the actuating loop. The dependence is also affected by the initial operational condition of the network. The thermal interaction, however, is different in that it is nonlinearly coupled with the hydrodynamic interaction.

Application of neural networks to predict the steady state performance of a Run-Around Membrane Energy Exchanger

2012 ◽  
Vol 55 (5-6) ◽  
pp. 1628-1641 ◽  
Author(s):  
Soheil Akbari ◽  
Howard B. Hemingson ◽  
David Beriault ◽  
Carey J. Simonson ◽  
Robert W. Besant
Keyword(s):  
Neural Networks ◽  
Steady State ◽  
Membrane Energy ◽  
Steady State Performance

Experimental investigation on the steady-state performance and piston stroke length control of a variable displacement wobble plate compressor

2005 ◽  
Vol 219 (2) ◽  
pp. 271-281 ◽  
Author(s):  
Changqing Tian ◽  
Chunpeng Dou ◽  
Xianting Li ◽  
Yunfei Liao
Keyword(s):  
Experimental Investigation ◽  
Steady State ◽  
Test Data ◽  
Air Conditioning ◽  
Volumetric Efficiency ◽  
Stroke Length ◽  
Variable Displacement ◽  
Rotary Speed ◽  
Piston Stroke ◽  
Steady State Performance

The aim of this paper is to find out the steady-state performance and piston-stroke-length control behaviour of a variable displacement wobble-plate compressor for an automotive air-conditioning system by experimental investigation. First, a new method and device to measure the piston stroke length of the variable displacement compressor has been developed, with which the test bench for the variable displacement compressor has been set up. Second, the steady-state performance of the variable displacement compressor, such as the relative volumetric efficiency and the relative isentropic efficiency at partial piston stroke length, has been obtained. The influence of the work condition and compressor rotary speed on the relative volumetric efficiency can be neglected according to the test data. Finally, the critical wobble-plate case pressure is proposed in this paper to judge whether the piston stroke length will change or not. The critical wobble-plate case pressure when the piston stroke length decreases is greater than that when the piston stroke length increases, which is less influenced by the piston stroke length itself from the test data. The higher the compressor discharge pressure or rotary speed, the greater the critical wobble-plate case pressure. The piston stroke length can be adjusted automatically along with the air-conditioning load when the compressor rotary speed or air conditioning load changes.

Applying Static Fault Detection and Diagnosis Methods to Transient Air Conditioning Data Using an Equilibrium Prediction

2019 ◽  
Author(s):  
Austin Rogers ◽  
Fangzhou Guo ◽  
Bryan Rasmussen
Keyword(s):  
Steady State ◽  
Fault Detection ◽  
Equilibrium Point ◽  
Air Conditioning ◽  
Fault Detection And Diagnosis ◽  
Thermal Mass ◽  
Static Models ◽  
Transient Data ◽  
Detection And Diagnosis ◽  
Air Conditioning Systems

Abstract Fault detection and diagnosis methods for air conditioning systems typically apply static models after filtering out transient data using a steady state filter. However, air conditioning systems operating in the field often do not achieve a meaningful steady state and therefore the models cannot be applied because only transient data is available. This paper proposes a solution to this problem by predicting the equilibrium point using an exponential regression. The transient response of many system parameters such as cooling capacity, airflow, and refrigerant mass flow may be approximated as a first order dynamic response because the thermal mass in the system dominates other higher order dynamics. The best-fit for a decaying exponential will therefore yield a prediction for the equilibrium point, and static models may then be applied, thus enabling the use of static models with transient data. The method’s performance is quantified using both randomly generated data (Monte Carlo simulations) and the measured response of a field-operating system during both fault-free and faulty operation.

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