Desiccant technology is a category of HVAC equipment used for dehumidification. A desiccant material is a material that attracts and holds large amounts of water vapor. Desiccant materials are used in complete desiccant cooling units, air pretreatment devices, and HVAC system enhancements. The instructional module has been developed to introduce engineering students to desiccant technology and the use of desiccant systems. In the typical engineering curriculum, a number of courses could contain topics related to desiccant systems. Thermodynamics, heat transfer, HVAC, thermal systems design, and alternate energy systems courses are appropriate for desiccant related topics. The instructional module contains lecture material and review questions and exercises relating to desiccant systems and their uses.

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Agriculture and Agri-Food Canada (AAFC), the Ontario Greenhouse Vegetable Growers Association (OGVG), and Queen’s University’s Solar Calorimetry Laboratory (SCL) are undertaking a joint project to evaluate the energy and crop-yield benefits of operating commercial greenhouses in isolation from the outdoor environment, i.e., eliminating natural or forced ventilation to the exterior. Implementing such a scheme requires “closing” the greenhouse envelope and the installation of an active air-conditioning system to control temperature and moisture levels that could be harmful to crop growth. To this end, a prototype air-conditioning system, centered around a liquid desiccant dehumidifier, was designed, constructed and instrumented such that its thermal and functional performance could be evaluated over extended periods. The prototype unit was installed in a “research” greenhouse located at the Agriculture Canada, Greenhouse and Processing Crops Research Center (GPCRC) located in Harrow, Ontario. Both the novel air-conditioning and monitoring systems were implemented during the course of the thesis and operated for two preliminary crop trials to characterize system performance and identify aspects needing further refinement. Data obtained over these two initial periods, indicated that, the latent and sensible cooling capacity of the novel desiccant system averaged: 2.25 kW and -0.25 kW, respectively, during the severe summer trial; and 1.25 kW and -0.1 kW, respectively, during the milder spring trial. Values obtained from the preliminary monitored data also indicate that the liquid desiccant unit operated at electrical and thermal coefficients of performance (COPs) between 0.74 and 3.1 and between 0.15 and 0.52, respectively. Finally, using the monitored data, a simple regression-based empirical model was formulated to describe the average performance of the liquid desiccant unit. This was attempted to illustrate how performance results could be generalized to assist in the future design of similar commercial-scale systems. The results of this part of the thesis indicated, however, that further test data is required to confidently characterize the unit’s performance. As well, it was concluded that addition instrumentation (specifically, the addition of a meter to measure the flowrate of the regenerator air-stream) would enhance the potential to develop a practical performance correlation. / Thesis (Master, Mechanical and Materials Engineering) -- Queen's University, 2013-11-01 14:12:54.326

Field experiments were conducted at Carman, Manitoba to determine the effect of tank-mixing different contact herbicides with glyphosate and time of application of harvest aid herbicides on residue accumulation in dry bean seed and the effect of tank-mixing a contact herbicide with glyphosate on weed control. Carfentrazone-ethyl in mixture with glyphosate was the least effective harvest aid herbicide and did not fully desiccate plant parts or reduce glyphosate residues in the seed to less than 2 ppm. Saflufenacil, diquat, flumioxazin, and glufosinate in mixture with glyphosate effectively desiccated all plant and reduced glyphosate residue accumulation in the seed. Saflufenacil in mixture with glyphosate provided the most consistent efficacy on three weed species. Time of application of harvest aid herbicides influenced residue accumulation and yield; however, all harvest aids applied at or after 75% pod colour change had no negative effect on yield and significantly reduced the risk of residue accumulation.

ASHRAE Standard 139 provides parameters which are used in the desiccant industry to calculate the performance of a desiccant dehumidifier. This performance can be obtained from any manufacturer by means of performance curves or selection software. However, these performance parameters are generally rated at sea-level conditions. Although some manufacturers provide a means for estimating the performance at altitude based on sea-level conditions, there is no set methodology that is accepted by all. The scope of this project involves investigating how the performance parameters are affected by altitude and develop a general methodology that can be applied to any desiccant wheel. Mississippi State University and the National Renewable Energy Laboratory both conducted tests and compared the results. It was found that, by keeping mass flow rate, inlet temperature, and inlet humidity ratio constant between sea-level and altitude, the pressure drop through the wheel was influenced the most by altitude.

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Radiant heating and cooling has a reputation of increasing the comfort level and reducing the energy consumption of buildings. The main advantages of radiant heating and cooling are low operational noise and reduced fan power cost. Radiant heating and cooling has been supplied in several forms, including floor heating, ceiling heating and cooling, radiant panels and façade heating and cooling. Among them, façade heating and cooling is the most recently developed system. This dissertation provides a comprehensive study of several technical issues relative to radiant heating and cooling systems that have received little attention in previous research. The following aspects are covered in this dissertation: First, a heat transfer model of mullion radiators, one type of façade heating and cooling, is developed and verified by measured performance data. The simulation demonstrates that the heating or cooling capacity of mullion radiators is a semi-linear function of supply water temperature and is affected by the thermal conductive resistance of mullion tubes, the room air temperature, the supply water flow rate, and the outside air temperature. Second, the impact of the positions of radiators on energy consumption and thermal comfort is studied. This dissertation compares the heating load and comfort level as measured by uniformity of operative temperature for two different layouts of radiators in the same geometric space. The air exchange rate has been identified as an important factor which affects energy saving benefits of the radiant heating systems. Third, the infiltration and the interaction of infiltration and mechanical ventilation air to produce moisture condensation in a radiantly cooled office are examined. The infiltration of the studied office is also explored by on-site blower door measurement, by analyzing measured CO2 concentration data, and through modeling. This investigation shows the infiltration level of the studied office to range between 0.46 and 1.03 air changes per hour (ACH). Fourth, the integrated sensible heating and cooling system is simulated and compared with a single duct variable air volume (VAV) system. The results show that, at the current infiltration level, the studied sensible heating and cooling system with an integrated active desiccant ventilation unit consumes 5.6% more primary energy than a single duct VAV system; it would consumes 11.4% less primary energy when the system is integrated with a presumed passive desiccant ventilation unit.

Radiant heating and cooling has a reputation of increasing the comfort level and reducing the energy consumption of buildings. The main advantages of radiant heating and cooling are low operational noise and reduced fan power cost. Radiant heating and cooling has been supplied in several forms, including floor heating, ceiling heating and cooling, radiant panels and façade heating and cooling. Among them, façade heating and cooling is the most recently developed system. This dissertation provides a comprehensive study of several technical issues relative to radiant heating and cooling systems that have received little attention in previous research. The following aspects are covered in this dissertation: First, a heat transfer model of mullion radiators, one type of façade heating and cooling, is developed and verified by measured performance data. The simulation demonstrates that the heating or cooling capacity of mullion radiators is a semi-linear function of supply water temperature and is affected by the thermal conductive resistance of mullion tubes, the room air temperature, the supply water flow rate, and the outside air temperature. Second, the impact of the positions of radiators on energy consumption and thermal comfort is studied. This dissertation compares the heating load and comfort level as measured by uniformity of operative temperature for two different layouts of radiators in the same geometric space. The air exchange rate has been identified as an important factor which affects energy saving benefits of the radiant heating systems. Third, the infiltration and the interaction of infiltration and mechanical ventilation air to produce moisture condensation in a radiantly cooled office are examined. The infiltration of the studied office is also explored by on-site blower door measurement, by analyzing measured CO2 concentration data, and through modeling. This investigation shows the infiltration level of the studied office to range between 0.46 and 1.03 air changes per hour (ACH). Fourth, the integrated sensible heating and cooling system is simulated and compared with a single duct variable air volume (VAV) system. The results show that, at the current infiltration level, the studied sensible heating and cooling system with an integrated active desiccant ventilation unit consumes 5.6% more primary energy than a single duct VAV system; it would consumes 11.4% less primary energy when the system is integrated with a presumed passive desiccant ventilation unit.

Air-conditioning systems driven by solar energy have can save primary energy and reduce peak power consumption, which is particularly important for utility providers in the summer months. Additionally solar cooling is a promising application of solar thermal technology since the cooling load is well correlated to the overall solar availability. Liquid desiccant air-conditioning, which uses a salt solution to dehumidify air, can be used in a thermally driven air-conditioning system and offers many benefits for solar applications including the ability to store solar energy in the form of concentrated liquid desiccant. The current work focuses on the Queen’s University Solar Liquid Desiccant Cooling Demonstration Project. In previous work, a pre-commercial Liquid Desiccant Air Conditioner (LDAC) was installed and experimentally characterized using a gas-fired boiler to provide heat. As part of the current study a 95m2 solar array was added as a heat source. The Solar LDAC was tested for 20 days in the summer of 2012 to evaluate performance. The solar LDAC was found to provide between 9.2kW and 17.2kW of cooling power with an overall thermal Coefficient of Performance (COP) of 0.40 and electrical COP of 2.43. The collector efficiency was 53%, and 40% of the required thermal energy was provided by the solar array. A model was developed in TRNSYS to predict the performance of the solar LDAC and simulation results were compared to the experimental results with reasonable accuracy. The validated model was then used to simulate the annual performance of the solar LDAC in Toronto, Ontario; Vancouver, British Columbia; and Miami, Florida. The highest performance was achieved in Miami, where an overall thermal COP of 0.48 was predicted. It is proposed that additional improvements be made to the system by replacing inefficient pumps and fans, adding desiccant storage, and improving the control scheme. / Thesis (Master, Mechanical and Materials Engineering) -- Queen's University, 2012-10-29 16:34:02.906