In this study, a novel counter-cross-flow run-around membrane energy exchanger (RAMEE) system was designed and tested in the laboratory. The RAMEE system consists of two (2) counter-cross-flow Liquid-to-Air Membrane Energy Exchangers (LAMEEs) to be located in the supply and exhaust air streams in the building Heating Ventilation and Air-Conditioning (HVAC) system. Inside each exchanger, a micro-porous membrane separates the air and liquid streams and allows transfer of the sensible and latent energy from the air stream to the liquid stream or vice-versa. The system exchanges sensible and latent energy between supply and exhaust air streams using a desiccant solution loop. The supply and exhaust air streams in the RAMEE can be located far apart from each other or adjacent to each other. The flexibility of non-adjacent ducting makes the RAMEE system a better alternative compared to available energy recovery systems for the retrofit of HVAC systems.<p> Two counter-cross-flow exchangers for the RAMEE system were designed based on an industry recommended standard which is to obtain a target overall system effectiveness of 65% for the RAMEE system at a face velocity of 2 m/s. The exchanger design was based on heat exchanger theory and counter-cross-flow design approach. An exchanger membrane surface aspect ratio (ratio of exchanger membrane surface height to exchanger length) of 1/9 and the desiccant solution entrance ratio (ratio of desiccant solution entrance length to exchanger length) of 1/24 were employed. Based on different heat transfer case studies, the energy transfer size of each exchanger was determined as 1800 mm x 200 mm x 86 mm. ProporeTM was used as the membrane material and Magnesium-Chloride solution was employed as the desiccant solution.<p> The RAMEE performance (sensible, latent and total effectiveness) was evaluated by testing the system in a run-around membrane energy exchanger test apparatus by varying the air stream and liquid solution-flow rates at standard summer and winter operating conditions. From the test data, the RAMEE effectiveness values were found to be sensitive to the air and solution flow rates. Maximum total effectiveness of 45% (summer condition) and 50% (winter condition) were measured at a face velocity ¡Ö 2 m/s. A comparison between the experimental and numerical results from the literature showed an average absolute discrepancy of 3% to 8% for the overall total system effectiveness. At a low number of heat transfer units, i.e. NTU = 4, the numerical and experimental results show agreement within 3% and at NTU = 12 the experimental data were 8% lower than the simulations. The counter-cross-flow RAMEE total system effectiveness were found to be 10% to 20% higher than those reported for a cross-flow RAMEE system by another researcher.<p> It is thought that discrepancies between experimental and predicted results (design and numerical effectiveness) may be due to the mal-distributed desiccant solution-flow, desiccant solution leakage, lower than expected water vapor permeability of the membrane, uncertainties in membrane properties (thickness and water vapor permeability) and heat loss/gain effects. Future research is needed to determine the exact cause of the discrepancies.

<p>The main objective of this thesis is to investigate the energetic, economic and environmental impact of utilizing a novel Run-Around Membrane Energy Exchanger (RAMEE) in building HVAC systems. The RAMEE is an energy recovery ventilator that transfers heat and moisture between the exhaust air and the fresh outdoor ventilation air to reduce the energy required to condition the ventilation air. The RAMEE consists of two exchangers made of water vapor permeable membranes coupled with an aqueous salt solution.</p> <p>In order to examine the energy savings with the RAMEE, two different buildings (an office building and a health-care facility) were simulated using TRNSYS computer program in four different climatic conditions, i.e., cold-dry, cool-humid, hot-humid and hot-dry represented by Saskatoon, Chicago, Miami and Phoenix, respectively. It was found that the RAMEE significantly reduces the heating energy consumption in cold climates (Saskatoon and Chicago), especially in the hospital where the required ventilation rate is much higher than in the office building. On the other hand, the results showed that the RAMEE must be carefully controlled in summer to minimize the cooling energy consumption.</p> <p>The application of the RAMEE in an office building reduces the annual heating energy by 30% to 40% in cold climates (Saskatoon and Chicago) and the annual cooling energy by 8% to 15% in hot climates (Miami and Phoenix). It also reduces the size of heating equipment by 25% in cold climates, and the size of cooling equipment by 5% to 10% in hot climates. The payback period of the RAMEE depends on the air pressure drop across the exchangers. For a practical pressure drop of 2 cm of water across each exchanger, the payback of the RAMEE is 2 years in cold climates and 4 to 5 years in hot climates. The total annual energy saved with the RAMEE (including heating, cooling and fan energy) is found to be 30%, 28%, 5% and 10% in Saskatoon, Chicago, Miami and Phoenix, respectively.</p> <p>In the hospital, the RAMEE reduces the annual heating energy by 58% to 66% in cold climates, and the annual cooling energy by 10% to 18% in hot climates. When a RAMEE is used, the heating system can be downsized by 45% in cold climates and the cooling system can be downsized by 25% in hot climates. For a practical range of air pressure drop across the exchangers, the payback of the RAMEE is immediate in cold climates and 1 to 3 years in hot climates. The payback period in the hospital is, on average, 2 years faster than in the office building). The total annual energy saved with RAMEE is found to be 48%, 45%, 8% and 17% in Saskatoon, Chicago, Miami and Phoenix, respectively. The emission of greenhouse gases (in terms of CO₂-equivalent) can be reduced by 25% in cold climates and 11% in hot climates due to the lower energy use when employing a RAMEE.</p>

<p>The main objective of this thesis is to investigate the energetic, economic and environmental impact of utilizing a novel Run-Around Membrane Energy Exchanger (RAMEE) in building HVAC systems. The RAMEE is an energy recovery ventilator that transfers heat and moisture between the exhaust air and the fresh outdoor ventilation air to reduce the energy required to condition the ventilation air. The RAMEE consists of two exchangers made of water vapor permeable membranes coupled with an aqueous salt solution.</p> <p>In order to examine the energy savings with the RAMEE, two different buildings (an office building and a health-care facility) were simulated using TRNSYS computer program in four different climatic conditions, i.e., cold-dry, cool-humid, hot-humid and hot-dry represented by Saskatoon, Chicago, Miami and Phoenix, respectively. It was found that the RAMEE significantly reduces the heating energy consumption in cold climates (Saskatoon and Chicago), especially in the hospital where the required ventilation rate is much higher than in the office building. On the other hand, the results showed that the RAMEE must be carefully controlled in summer to minimize the cooling energy consumption.</p> <p>The application of the RAMEE in an office building reduces the annual heating energy by 30% to 40% in cold climates (Saskatoon and Chicago) and the annual cooling energy by 8% to 15% in hot climates (Miami and Phoenix). It also reduces the size of heating equipment by 25% in cold climates, and the size of cooling equipment by 5% to 10% in hot climates. The payback period of the RAMEE depends on the air pressure drop across the exchangers. For a practical pressure drop of 2 cm of water across each exchanger, the payback of the RAMEE is 2 years in cold climates and 4 to 5 years in hot climates. The total annual energy saved with the RAMEE (including heating, cooling and fan energy) is found to be 30%, 28%, 5% and 10% in Saskatoon, Chicago, Miami and Phoenix, respectively.</p> <p>In the hospital, the RAMEE reduces the annual heating energy by 58% to 66% in cold climates, and the annual cooling energy by 10% to 18% in hot climates. When a RAMEE is used, the heating system can be downsized by 45% in cold climates and the cooling system can be downsized by 25% in hot climates. For a practical range of air pressure drop across the exchangers, the payback of the RAMEE is immediate in cold climates and 1 to 3 years in hot climates. The payback period in the hospital is, on average, 2 years faster than in the office building). The total annual energy saved with RAMEE is found to be 48%, 45%, 8% and 17% in Saskatoon, Chicago, Miami and Phoenix, respectively. The emission of greenhouse gases (in terms of CO₂-equivalent) can be reduced by 25% in cold climates and 11% in hot climates due to the lower energy use when employing a RAMEE.</p>

In this study, a novel counter-cross-flow run-around membrane energy exchanger (RAMEE) system was designed and tested in the laboratory. The RAMEE system consists of two (2) counter-cross-flow Liquid-to-Air Membrane Energy Exchangers (LAMEEs) to be located in the supply and exhaust air streams in the building Heating Ventilation and Air-Conditioning (HVAC) system. Inside each exchanger, a micro-porous membrane separates the air and liquid streams and allows transfer of the sensible and latent energy from the air stream to the liquid stream or vice-versa. The system exchanges sensible and latent energy between supply and exhaust air streams using a desiccant solution loop. The supply and exhaust air streams in the RAMEE can be located far apart from each other or adjacent to each other. The flexibility of non-adjacent ducting makes the RAMEE system a better alternative compared to available energy recovery systems for the retrofit of HVAC systems.<p> Two counter-cross-flow exchangers for the RAMEE system were designed based on an industry recommended standard which is to obtain a target overall system effectiveness of 65% for the RAMEE system at a face velocity of 2 m/s. The exchanger design was based on heat exchanger theory and counter-cross-flow design approach. An exchanger membrane surface aspect ratio (ratio of exchanger membrane surface height to exchanger length) of 1/9 and the desiccant solution entrance ratio (ratio of desiccant solution entrance length to exchanger length) of 1/24 were employed. Based on different heat transfer case studies, the energy transfer size of each exchanger was determined as 1800 mm x 200 mm x 86 mm. ProporeTM was used as the membrane material and Magnesium-Chloride solution was employed as the desiccant solution.<p> The RAMEE performance (sensible, latent and total effectiveness) was evaluated by testing the system in a run-around membrane energy exchanger test apparatus by varying the air stream and liquid solution-flow rates at standard summer and winter operating conditions. From the test data, the RAMEE effectiveness values were found to be sensitive to the air and solution flow rates. Maximum total effectiveness of 45% (summer condition) and 50% (winter condition) were measured at a face velocity ¡Ö 2 m/s. A comparison between the experimental and numerical results from the literature showed an average absolute discrepancy of 3% to 8% for the overall total system effectiveness. At a low number of heat transfer units, i.e. NTU = 4, the numerical and experimental results show agreement within 3% and at NTU = 12 the experimental data were 8% lower than the simulations. The counter-cross-flow RAMEE total system effectiveness were found to be 10% to 20% higher than those reported for a cross-flow RAMEE system by another researcher.<p> It is thought that discrepancies between experimental and predicted results (design and numerical effectiveness) may be due to the mal-distributed desiccant solution-flow, desiccant solution leakage, lower than expected water vapor permeability of the membrane, uncertainties in membrane properties (thickness and water vapor permeability) and heat loss/gain effects. Future research is needed to determine the exact cause of the discrepancies.