A study on the performances of the liquid-desiccant air-conditioning system using different combination units
| Autor: | Sheng-Hong Chen, 陳勝宏 |
|---|---|
| Rok vydání: | 2019 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 107 This study investigates the air condition in different states and the coefficient of performance (COP) for the NanoCOOL system (the liquid desiccant air-conditioning system) in summer. Under different weather conditions, the three units of the NanoCOOL system are operated in different combinations, and it is desirable to reduce the system’s electric power consumption and reach the acceptable air conditions in the locker rooms. The NanoCOOL system is divided into three main units, air handling unit (AHU), liquid desiccant system (LDS) and polyvalent unit (PU). AHU is an air handling unit with the water coil. The water coil either cools or heats the air by the cold or hot water; LDS is a liquid desiccant system that is the main unit for dehumidification and regeneration; PU is a polyvalent unit that supplies hot and cold water. The desiccant used in this study is a lithium chloride solution, and the hot and cold water is supplied by the polyvalent unit. Cold water improves the dehumidification effect of the lithium chloride solution, and the hot water is used to regenerate the lithium chloride solution after dehumidification. The hot and cold water of the polyvalent unit flows through the AHU water coil to control the temperature of the dehumidified air. Compared with the traditional air conditioning system, this system can achieve independent control of temperature and humidity. The experimental observations use four modes: Mode 1: all units are in operation, Mode 2: polyvalent unit (PU) and air handling unit (AHU) are in operation, Mode 3: liquid desiccant system (LDS) and air handling unit (AHU) are in operation, Mode 4: only the air handling unit (AHU) is in operation. The liquid desiccant dehumidification system can directly dehumidify the air, and the driving force is the vapor pressure difference between the air and the surface of liquid desiccant solution. In Mode 1, the system can effectively reduce the humidity ratio of the air by 7.7 ∼ 10.3 g/kg, and keep the humidity ratio of the supply air between 9.6 ∼ 11 g/kg. The temperature of the men and women locker rooms are 27 C, and the humidity ratio is 15 ∼ 18 g/kg for the men locker room and 12 ∼ 15 g/kg for the women locker room respectively. The opreation of Mode 2 is similar to the traditional air conditioner, and the air is cooled below the dew point temperature to condense the water vapor. The humidity ratio is only reduced about 7.3 g / kg in Mode 2. In Mode 3, only the liquid desiccant system is in operation, and the dehumidification effect is not very significant. During the dehumidification process the water vapor state changes to a liquid state, and releases its latent energy. The released latent energy is absorbed by the air and lithium chloride solution, and the temperature of air and lithium chloride solution rise. In Mode 1, the COP is about 0.9 to 1.27, the COP in Mode 2 is about 1.48, but the dehumidification efficiency in Mode 2 is lower than that of Mode 1. In Mode 3, if the regeneration process of liquid desiccant is built, it is possible to achieve the desired humidity conditions. Mode 4 directly supplies the ambient air into the indoor space when the temperature and humidity conditions are comfortable. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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