Liquid-to-air Membrane Energy Exchanger Research Articles

Performance evaluation of an innovative liquid desiccant air-conditioning system directly integrating a heat pump with two membrane energy exchangers

For high moisture removal applications with improved indoor air quality, the use of liquid-to-air membrane energy exchangers (LAMEEs) in liquid desiccant (LD) air-conditioning systems has been suggested in the literature. This study introduces a novel configuration for a heat pump LD system to improve its dehumidification and energy use. The evaporator and condenser coils of the heat pump (HP) are embedded in the LD channels of two LAMEEs; one is an internally cooled dehumidifier (ICD), and the other is an internally heated regenerator (IHR). These LAMEEs are designed to directly use the HP condenser coils for the IHR's regeneration process while also effectively controlling the local temperature rise of the LD solution inside the ICD. An integrated CFD model for both the ICD and the IHR is simultaneously solved, considering the coupling of the HP components and the closed loop of the LD solution. This model, which counts all existing balances of energy, mass, and salt content in various components, determines the condensing temperature employed in the regeneration process at each operational condition. This system-level model, which requires few inputs, is novel and very reliable for evaluating the overall performance of the proposed system in terms of specific dehumidification rates and COP. Case studies were carried out using the annual dehumidification design conditions of five Middle Eastern cities known for their hot and humid climates. For the cities of Sharm El Sheikh and Dammam, respectively, the system achieved promising results with specific dehumidification rates of 130.3 and 172.2 g/(m2.h) and system COPs of 6.38 and 5.67, when the temperature and specific humidity of outside fresh air of (30 °C, 19 g/kg) and (32.8 °C, 23.2 g/kg) were cooled and dehumidified to (20.18 °C, 6.52 g/kg) and (21.0 °C, 6.61 g/kg). Using the regeneration air flow rate as high as possible boosts the performance of the proposed HPLD system, concluding that the system is preferable for all-fresh-air handling units.

Innovative method to reduce frost formation in liquid-to-air membrane energy exchangers (LAMEE) based on 3D CFD simulation

Frost formation is an important and challenging problem in the proper operation of ventilation systems. In this study, a novel model is developed to predict the amount of frost formation in a Liquid-to-Air Membrane Energy Exchanger (LAMEE) based on the 3-Dimensional Computational Fluid Dynamics (CFD) technique. This model can be a robust way to find and analyze different proposed methods to combat frost. The results show that the presence of the membrane reduces the mass of frost compared to the impermeable surface by approximately 60% due to the mass transfer phenomenon. Moreover, the variations of air temperature along the LAMEE are sharper than the changes in humidity ratio, which is an important reason for more frost forming. Condensed Humidity Ratio (CHR) is presented as a valid criterion for analyzing the distribution of frost formation in heat and energy exchangers. Furthermore, an innovative method is proposed based on 3-fluid LAMEE to reduce frost formation. In the proposed method, the solution temperature is controlled with another fluid that flows in tubes located in the solution channel. Therefore, this model control heat transfer between air and solution flows in different parts and moderate air temperature variations for vapor reach the saturation line in a low humidity ratio. The developed CFD model predicts that the frost formation in the proposed LAMEE is around 25–28% saturation less than the typical LAMEE at an equal sensible cooling capacity.

Performance study of heat and mass transfer in a counterflow liquid to air membrane-based parallel-plate dehumidifier

Liquid to air membrane energy exchanger (LAMEE) is the most important component in a liquid desiccant air conditioning system. Three main configurations of LAMEE are presented in the literature: co-current, counterflow, and cross-counter flow. In this paper, we evaluated the performance of a counterflow LAMEE dehumidifier in terms of its cooling capacity (CC) and moisture removal rate (MRR). A numerical model was developed and validated with experimental results. The impact of solution properties and inlet air characteristics on the LAMEE’s performance were investigated. Simulation results show that CC and MRR are enhanced by decreasing the temperature and increasing the concentration of the liquid desiccant simultaneously. In order to obtain an optimal performance of the LAMEE, the solution mass flow rate should be equal to or slightly higher than the inlet air mass flow rate. On the other hand, we found that both CC and MRR increase with increasing inlet air temperature and relative humidity. Even though solution properties and inlet air characteristics affect the MRR and the CC, they have a negligible effect on the required air sensible cooling to meet the supply air condition (Qsen). The characteristics of outlet air provided by the LAMEE are in a stable state condition, which proves that the LAMEE has a wide range of adaptability in different operating conditions.

A model for predicting the effect of crystallization fouling on moisture transfer in membrane energy exchangers

Crystallization fouling is an important phenomenon that impacts the design and operation of membrane-based separation processes. Recently, membranes have been applied to separate aqueous salt solutions and air streams for moisture control in buildings using liquid-to-air membrane energy exchangers (LAMEEs). LAMEEs are efficient energy exchangers that use a semi-permeable hydrophobic membrane to separate air and aqueous salt solutions, while allowing simultaneous heat and moisture exchange between the fluids. However, in some design and operating conditions, crystallization fouling occurs which hinders the performance of LAMEEs. The main objective of this paper is to develop a model which predicts the fouling rate for membranes in LAMEEs. The semi-empirical model estimates the decline in moisture transfer rate by taking into account the surface blockage of the membrane due to crystallization fouling. The model is validated with experimental data available in the literature. The model can then be used to predict the theoretical crystallization fouling limits and the effect of design and operational parameters on fouling rates. For example, the initial fouling rate is four times higher for a supersaturated solution (3% above saturation) than for a saturated solution. The main contribution of this study is that the developed semi-empirical model can help the designers predict the fouling rate for long-term periods and determine the cleaning intervals of the LAMEE.

Calibration of indirect methods to detect the onset of fouling in a liquid-to-air membrane energy exchanger

Fouling is a perennial problem that diminishes the performance of heat and membrane exchangers. Therefore, the onset of fouling needs to be timely detected in operating exchangers so that corrective measures can be implemented to mitigate the growth of fouling.This paper presents the sequel to the research that is reported in a previous paper (Olufade and Simonson, 2018). In the previous paper, three indirect methods that are based on the analysis of moisture transfer measurements were applied to detect fouling in a liquid-to-air membrane energy exchanger (LAMEE). In this paper, the indirect methods are calibrated against a benchmark direct method (digital microscopy) to detect the onset of fouling in the LAMEE. Scanning electron microscopy (SEM) is used for autopsy of tested membranes and also serves as a concomitant direct method. The calibrated indirect methods are then applied to detect the onset of fouling at the same condition of their calibration and extrapolated to a different condition.Digital microscopy is found to be three to eight times more sensitive to detect the onset of fouling than the three indirect methods. In addition, there is reasonable agreement between the results obtained using digital microscopy and SEM. The results indicate that the calibrated indirect methods are able to detect the onset of fouling within the uncertainty limits of the digital microscopy method only when they are applied to the same condition of calibration. Care must, therefore, be exercised if the indirect methods are extrapolated to operating conditions that are different from their calibration.

Optimal design, sizing and operation of heat-pump liquid desiccant air conditioning systems

Heat-pump liquid desiccant air conditioning (heat-pump LDAC) systems can provide effective control over indoor air humidity and provide healthy environments for occupants. Although several studies have been recently conducted on heat-pump LDAC systems, no information is available in the scientific literature about how to design, size, and operate these systems to optimize energy efficiency. A novel thermodynamic analysis for heat-pump LDAC systems is developed and presented in this paper. The thermodynamic analysis is aimed to guide engineers and researchers to identify optimal operating points for the design, sizing, and operation of heat-pump LDAC systems. This thermodynamic analysis reveals a new fundamental capacity matching index for heat-pump LDAC systems that optimizes energy efficiency (increasing COP by 50%). The proposed thermodynamic analysis is demonstrated in this study on a heat-pump membrane LDAC system, which uses two liquid-to-air membrane energy exchangers (LAMEEs) as the dehumidifier and regenerator.

3D computational fluid dynamics simulation of a 3-fluid liquid-to-air membrane energy exchanger (LAMEE)

In this article, a 3-fluid liquid-to-air membrane energy exchanger (LAMEE) prototype has been modeled using 3D computational fluid dynamics (CFD) technique. Applying advanced CFD simulation along with UDF (User Defined Function) and UDS (User Defined Scalar) external computer programs are major efforts of the present study which have overcome some computational restrictions of conventional numerical simulation software. Therefore, additional equations of mass and energy transfer are accompanied with fundamental governing equations of Newtonian fluid flow to explore the complexity of numerical analysis. The rates of conjugate heat and moisture transfer through the membrane, air and desiccant exit temperatures and the cooling effect of the refrigeration tubes are evaluated and shown in detail. The calculated temperature and humidity ratio at the outlet of the 3-fluid LAMEE agree well with available experimental data. The present CFD simulation reveals the diverse cooling effect of the different refrigeration tubes in the 3-fluid LAME depending on their individual geometrical location. The refrigeration tubes increase the sensible, latent and total effectiveness, moisture removal rate and sensible cooling capacity 72%, 29%, 41%, 13.0 gv/h and 8.7 W, respectively. The obtained temperature and humidity ratio contours and flow patterns throughout the 3-fluid LAMEE reveal the mechanisms of dehumidification, cooling and phase change.

Thermal energy analysis on liquid desiccant air conditioning system at different desiccant solution parameters

Selection of suitable liquid desiccant operating parameters plays a significant role in the design of energy efficient liquid desiccant air conditioning system. To achieve same dehumidification rate from ambient air, different combinations of solution parameters (heat capacity ratio, concentration, and vapor pressure) could be employed in the system. Considering dehumidifier air inlet condition and dehumidification rates are fixed, an analytical study is carried out on the thermal energy analysis of the system at different solution operating parameters. Operating parameters considered in this study are solution concentrations ( Cs = 0.25, 0.3, 0.35 and 0.40) and heat capacity ratios ([Formula: see text] = 2.5, 3, 4 and 5). Control volume which includes a pair of air and solution channels (half width channels) of full scale liquid-to-air membrane energy exchangers (LAMEE) has been chosen to analyze the energy transfer between air and solution. The results indicate system requires lesser chiller load ( Qchiller) at high concentration and low heat capacity ratio ( Cs = 0.40 and [Formula: see text] = 2.5) which is 0.29 kW to achieve 0.61 kW cooling load. This is 99% lesser than the Qchiller at high concentration and high heat capacity ratio ( Cs = 0.40 and [Formula: see text] = 5) and 30% lesser than the Qchiller at low concentration and low heat capacity ratio ( Cs = 0.25 and [Formula: see text] = 2.5). Solution heat addition rate ( Qadd) per kW cooling capacity ( Qcc) at this solution condition is found as 0.85 kW.

Experimental study of liquid to air membrane energy exchanger (LAMEE) performance by measuring its temperature fields

Many studies have already been conducted to assess liquid to air membrane energy exchanger (LAMEE) performance by numerical and experimental methods. However, the LAMEE temperature field is still an unknown area due to the operation difficult. In this study, an experimental method is adopted to investigate the performance of LAMEE by measuring its temperature fields. The effects of main parameters such as the solution temperature, solution concentration and air relative humidity, are investigated. The results show that the air relative humidity and solution temperature have negative influences on the LAMEE efficiency. It is found that the total effectiveness reduces by 2.7% and 7.7% when the air relative humidity increases from 62% to 74%, and the solution temperature changes from 18 °C to 26 °C, respectively. Increasing the solution concentration decreases the sensible effectiveness while enhancing the latent and total effectiveness. The total effectiveness increases 3.5% as the solution concentration increase from 30% to 39%. These results are useful to optimize the LAMEE in the future.

Characterization of the Evolution of Crystallization Fouling in Membranes.

Liquid-to-air membrane energy exchangers (LAMEEs) are promising in heating, ventilating, and air-conditioning applications because they are able to use semipermeable membranes to transfer heat and moisture between air and liquid desiccant streams. However, the development of crystallization fouling in membranes may pose a great risk to the long-term performance of LAMEEs. The main aim of this paper is to characterize the evolution of crystallization fouling in membranes through the use of both noninvasive and invasive methods. Noninvasive methods are used to study the development of fouling in the LAMEE by monitoring the changes in moisture flux through the membrane and overall moisture-transfer resistance of the LAMEE. On the other hand, invasive methods are implemented to characterize fouled membranes by using optical microscopy and scanning electron microscopy (SEM) to depict the morphology of crystal deposits and energy-dispersive X-ray spectroscopy (EDX) to identify the composition of the deposits. Experiments are performed by using air to dehydrate MgCl2(aq) at two operating conditions of low and high fouling rates. The results show that the moisture flux decreases and the moisture-transfer resistance increases more considerably during the test at the high fouling rate than in the test at the low fouling rate. SEM micrographs show that cake crystal deposits cover the membrane surface in the test at the high fouling rate, whereas only few crystal particles are observed on the membrane in the test at the low fouling rate. Furthermore, the crystal deposits undergo more structural changes in the tests at the high fouling rate than in the tests at the low fouling rate, possibly because of the higher moisture transfer rate through the membrane in the tests at the high fouling rate. Finally, the SEM–EDX analysis confirms that the crystal deposits primarily consist of Mg, Cl, and O elements.

Application of indirect non-invasive methods to detect the onset of crystallization fouling in a liquid-to-air membrane energy exchanger

Liquid-to-air membrane energy exchangers (LAMEEs) use semi-permeable membranes and are designed to transfer heat and moisture between air and liquid streams in heating, ventilating, and air-conditioning (HVAC) systems. However, crystallization fouling in membranes is possible in practical HVAC applications, and this may lead to severe degradation in the performance of LAMEEs.The main aim of this paper is to apply three indirect non-invasive methods to detect the onset of crystallization fouling in a LAMEE. The methods are used to detect fouling by analyzing experimental measurements of moisture flux and moisture transfer resistance. The experimental tests involve dehydrating varying concentrations of MgCl2(aq) desiccant solutions using two types of membrane with different vapor diffusion resistances (VDRs).The results confirm that two of the three methods can effectively detect the onset of crystallization fouling in the LAMEE. Thus, the methods can be used for online monitoring of operating LAMEEs in order to timely identify the initiation of fouling. The results also show that the membrane with a lower VDR produces a higher moisture flux which leads to a higher degree of fouling than the membrane with higher VDR.

Detection of crystallization fouling in a liquid-to-air membrane energy exchanger

A liquid-to-air membrane energy exchanger (LAMEE) is a new development for air-conditioning that facilitates the exchange of heat and moisture between air and liquid streams, through a semi-permeable membrane. However, fouling may occur in the membrane and severely lower the performance of a LAMEE.The primary aim of this study is to develop a test facility and use non-invasive methods to detect crystallization fouling in membranes. The fouling detection methods, which consist of an uncertainty analysis and a statistical test, are applied to confirm or reject the occurrence of fouling in a LAMEE for several tests in which MgCl2(aq) desiccant solution is dehydrated for approximately 12 h.The results indicate that crystallization fouling can be detected in a LAMEE with the methods presented. Crystallization fouling was found to reduce the rate of moisture transfer through the membrane by up to 60%. Furthermore, a major contribution of this paper is that reducing the rate of moisture transfer through a membrane can delay crystallization fouling in a LAMEE.

Performance testing of 2-fluid and 3-fluid liquid-to-air membrane energy exchangers for HVAC applications in cold–dry climates

Liquid-to-air membrane energy exchangers (LAMEEs) can avoid the problem of desiccant droplets carryover by using semi-permeable membranes to separate the air and desiccant solution streams. The aim of this study is to test and compare the heat and moisture transfer performances between the air and desiccant solution inside a novel 3-fluid LAMEE and a 2-fluid LAMEE under air heating and humidifying conditions. The effect of flow maldistribution on the deterioration of the 3-fluid LAMEE’s performance is estimated, and an experimental study of the feasibility of membrane pre-tension to reduce flow maldistribution caused by membrane deflections in flat-plate LAMEEs is presented. Unlike heat exchangers where the lowest possible outlet hot fluid temperature is equal to the inlet cold fluid temperature, experimental data show that the outlet desiccant solution (hot fluid) temperature in the 2-fluid LAMEE may be lower than the inlet air (cold fluid) temperature. This is attributed to the effect of the phase change energy associated with the air humidification process.

Optimal design of a hybrid liquid desiccant-regenerative evaporative air conditioner

This paper presents the optimal design of a hybrid liquid desiccant-regenerative evaporative air conditioner. A hybrid air conditioner was proposed which comprises a liquid-to-air membrane energy exchanger (LAMEE) as a desiccant dehumidifier and a regenerative heat and mass exchanger (RHMX) as an evaporative cooler. The air conditions across the LAMEE and the RHMX were achieved by two heat and mass transfer sub-models, and validation of the sub-models was conducted by comparison of the simulation results against the published experimental measurements. Intake air flow rate, LAMEE-to-total length ratio and working-to-intake air flow ratio are regarded as design variables. The simplified conjugate gradient method (SCGM) was employed as an optimization scheme to find the optimum set of design variables, which maximizes the room cooling capacity (RCC) of the proposed hybrid air conditioner. The influences of different design and operating conditions on the optimal RCC and the optimum set of design variables were studied.

Extension of the Concepts of Heat Capacity Rate Ratio and Effectiveness-Number of Transfer Units Model to the Coupled Heat and Moisture Exchange in Liquid-to-Air Membrane Energy Exchangers

The underlying concept of the standard effectiveness-number of transfer units (NTU) model is that the effectiveness of an exchanger can be correlated to two dimensionless parameters, namely, heat capacity ratio (Cr) and NTU. However, a limitation of this model is that it cannot account for the changes in effectiveness due to changes in operating temperature and humidity of simultaneous heat and moisture exchangers, specifically liquid-to-air membrane energy exchangers (LAMEEs). The purpose of this paper is to explain the reason for this limitation and also to explore the extension of the aforementioned concept of the effectiveness-NTU model to LAMEEs. The first contribution of this paper is to demonstrate that the reason for this limitation is that one of the simplifying assumptions of the standard effectiveness-NTU model, i.e., that Cr represents the ratio between the changes in the temperatures of the two fluid streams across an exchanger, is not applicable to LAMEEs. Further analysis in this paper yields two new fundamental dimensionless parameters that are analogous to Cr, termed effective Cr and effective m*, which represent the actual ratios between the changes in the temperatures and humidity ratios of the fluid streams. Then, it is shown that models analogous to the standard effectiveness-NTU model can be used to correlate the dependency of the effectiveness of LAMEEs on the operating temperature and humidity to effective Cr and effective m*.

Performance testing of a novel 3-fluid liquid-to-air membrane energy exchanger (3-fluid LAMEE) under desiccant solution regeneration operating conditions

Liquid-to-air membrane energy exchangers (LAMEEs) use semi-permeable membranes to transfer heat and moisture between air and desiccant solution, and prevent the transfer of desiccant droplets to the airside. A 2-fluid flat-plate LAMEE is composed of several adjacent air and desiccant solution channels each separated by a semi-permeable membrane. A 3-fluid LAMEE is the new generation of LAMEEs which has a structure similar to a 2-fluid flat-plate LAMEE. The novelty of the 3-fluid LAMEE is that it includes titanium tubes inside the desiccant solution channels to control the temperature of the desiccant solution along the exchanger. In this paper, the performances of a 2-fluid LAMEE and 3-fluid LAMEE are tested and compared under diluted desiccant solution regeneration operating conditions. Also studied are the effects of operating conditions (inlet heating water temperature, heating water mass flow rate, desiccant solution mass flow rate, and inlet desiccant solution temperature) on the performances of the 2-fluid and 3-fluid LAMEEs. For the chosen test conditions, results show that effectiveness and moisture removal rate of the 3-fluid LAMEE are higher than the 2-fluid LAMEE under the entire range of inlet heating water temperature, heating water flow rate, and desiccant solution flow rate studied. The effectiveness and moisture removal rate of the 3-fluid LAMEE increase as the inlet heating water temperature and/or flow rate increases. The sensible, latent, and total effectivenesses, and moisture removal rate of the LAMEE increase by 38%, 40%, 39%, and 6 times when the temperature of desiccant solution is maintained constant along the exchanger. Compared with the 2-fluid LAMEE, the sensible, latent, and total effectivenesses, and moisture removal rate of the 3-fluid LAMEE are improved by up to 104%, 141%, 128%, and 17 times, respectively.

Design and testing of a novel 3-fluid liquid-to-air membrane energy exchanger (3-fluid LAMEE)

Liquid-to-air-membrane energy exchangers (LAMEEs) are constructed with micro-porous semi-permeable membranes and transfer heat and water vapor between two separate fluids (air and liquid desiccant). Over the last decade, research has shown that LAMEEs can significantly reduce the energy consumption of HVAC systems. In this paper, a novel 3-fluid LAMEE prototype is designed and tested. The main objective of the proposed 3-fluid LAMEE is to enhance the performance (i.e. sensible, latent, and total effectivenesses, moisture removal rate, and sensible cooling capacity) of regular 2-fluid LAMEEs. The major difference between the proposed 3-fluid LAMEE and a 2-fluid flat-plate LAMEE is that, refrigeration tubes are placed inside the desiccant solution channels to enhance the cooling capacity and control the temperature of the desiccant solution along the length of the 3-fluid LAMEE. Water is used as the refrigerant in the current work. The main contribution of this paper is that it shows that the inlet temperature and mass flow rate of the cooling water have significant influences on the steady-state performance of the 3-fluid LAMEE. Compared to a 2-fluid LAMEE with the same design parameters, the sensible, latent, and total effectivenesses, moisture removal rate, and sensible cooling capacity of the 3-fluid LAMEE are improved by up to 69%, 28%, 39%, 54%, and 140% respectively, depending on the inlet temperature and mass flow rate of the cooling water.

Numerical modeling of fluid flow and coupled heat and mass transfer in a counter-cross-flow parallel-plate liquid-to-air membrane energy exchanger

In this paper, a numerical model is developed and applied to investigate the fluid flow and heat and mass transfer in a counter-cross-flow liquid-to-air membrane energy exchanger (LAMEE). An iterative finite-difference method is used to solve two-dimensional steady-state flow field and the coupled heat and moisture transfer equations for the liquid desiccant and air streams. The model is validated with experimental data, and the agreement is within ±10%. The results of the numerical model show that the phase change energy plays a key role in the establishment of the temperature and moisture content distributions in the LAMEE. In the process of air cooling and dehumidification, the liquid desiccant temperature is increased not only by the sensible heat transfer, but also by the moisture transfer. Also, the capacity of the liquid desiccant to absorb moisture from the air is shown to be affected by the sensible energy transfer between the two fluids. Moreover, it is shown that the counter-cross-flow LAMEE effectiveness is between the effectiveness of pure counter-flow and pure cross-flow LAMEEs with the same membrane area. It is recommended for a practical design that the aspect ratio and entrance ratio should be less than 0.2 and 0.1 respectively, in order to achieve a high performance of the counter-cross-flow design that approaches within 2% the performance of a counter-flow design. Alternately, the membrane area of the practical design can be increased slightly (by 10%) so that the counter-cross-flow LAMEE has the same performance as a counter-flow LAMEE.

Sensitivity of the performance of a flat-plate liquid-to-air membrane energy exchanger (LAMEE) to the air and solution channel widths and flow maldistribution

Liquid-to-air membrane energy exchangers (LAMEEs) are novel energy exchangers which use semi-permeable membranes to separate air and desiccant solution streams. The semi-permeable membrane allows simultaneous heat and water vapor transfer between the air and the desiccant solution streams. These exchangers, which include bonded elastic membranes, are prone to significant variations in the flow channel widths, which causes flow maldistribution, and this causes performance degradation. This paper uses a numerical model to show the sensitivity of the steady-state performance of a flat-plate LAMEE to the air and solution channel widths, when operated as a supply air dehumidifier and a diluted desiccant solution regenerator. Simulations show that, without air flow channel width variations, the effectiveness of both the dehumidifier and the regenerator can always be increased toward 1.0 by reducing the nominal air and solution channel widths. To account for variations in the air channel widths, which occur due to construction tolerances and pressure differences across the membrane, laminar fully developed flow equations are used to investigate the influence of random variations in the air channel widths on the performance (i.e. effectiveness and air pressure drop) of the flat-plate LAMEE. The main contribution of this paper is that it shows that there exists an optimal air channel width for flat-plate LAMEEs with flow maldistribution due to random variations in the air channel width. Decreasing the air channel width below this optimal value will result in a decrease in effectiveness. It is found that the optimum nominal air channel width for flat-plate LAMEEs may be 5–6mm and the optimum nominal solution channel width is 1–2mm.

A methodology for scaling a small-scale energy exchanger performance results to a full-scale energy exchanger

In energy exchangers, heat and moisture simultaneously transfer between two fluids (i.e. liquid and air) which are directly in contact or separated by a semi-permeable membrane. The membrane is permeable for water vapor but impermeable for liquids. Testing a full-scale energy exchanger is often expensive and time consuming, so a small-scale model of the energy exchanger, which is smaller and often simpler than the full-scale energy exchanger, can be used to predict the performance of the full-scale energy exchanger at different conditions. This paper presents a scaling methodology to investigate a similarity between small-scale and full-scale energy exchangers. The scaling methodology consists of 5 main steps: (1) develop and build a small-scale energy exchanger and a test facility to test the small-scale energy exchanger; (2) test the small-scale energy exchanger under various test conditions; (3) model the couple heat and mass transfer in the energy exchanger, and validate the model with the experimental data; (4) test a full-scale energy exchanger with similar design as the small-scale energy exchanger under various test conditions; and (5) investigate the similarity between the small-scale and full-scale energy exchangers. The similarity between a small-scale single-panel liquid-to-air membrane energy exchanger (LAMEE) and a full-scale LAMEE is investigated in this paper using the scaling methodology. A LAMEE is a novel flat-plate membrane-based energy exchanger where the heat and moisture transfer between air and solution streams through a semi-permeable membrane. The similarity results for the LAMEE show that the small-scale LAMEE effectiveness results can be used to predict the performance of the full-scale LAMEE within ±2% and ±4% uncertainty bounds.