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https://ptsldigital.ukm.my/jspui/handle/123456789/520495| Title: | A hybrid liquid desiccant air conditioning system for horticulture greenhouse |
| Authors: | Abdulrahman Th. Mohammad (P56238) |
| Supervisor: | Sohif Mat, Prof. Dr. |
| Keywords: | Air conditioning system Horticulture greenhouse Refrigeration and refrigerating machinery |
| Issue Date: | 20-Jan-2013 |
| Description: | A hybrid liquid desiccant air conditioning system has been tested and simulated to investigate the technical feasibility of cooling system for greenhouse using weather data for Malaysia. Lithium chloride has been used as a liquid desiccant for the process of absorption in the dehumidifier and R22 as a refrigerant in the vapor compression cycle. The goal of the present investigation is to evaluate the performance of the system and its units. The hybrid air-conditioning system consists of three major units: 1) The sensible heat removal unit (SHRU) using a vapor compression heat pump to handle the sensible heat from the greenhouse. 2) Latent heat removal unit (LHRU) using liquid desiccant to remove the latent heat of fresh air. 3) Direct evaporative cooler (DEC) to meet the induce conditions for the plant to grow and flower. In the combined system, the humidity of 20% of fresh air is adjusted by a direct contact with the lithium chloride in the packing bed and then mixed with 80% of return air before entering the evaporator. The building energy analysis software DOE-2.1E was used to calculate cooling load of the greenhouse. The calculations aim to investigate the reduction in thermal gains and cooling load requirements using three different greenhouse models. The double envelope roof with shading effectively reduces the maximum cooling load as compared with the other two models. This double envelope roof with shading was then used for further evaluations and development. At maximum cooling load of the greenhouse which happens on the 7th September of the year, cooling load reduction of about 24.1% was achieved when the outdoor temperature were 33 °C dry-bulb and 25 °C wet-bulbs. The simulation model of liquid desiccant system is provided using an artificial neural network (ANN) to predict the performance of the dehumidifier and regenerator in terms of moisture removal rate and the effectiveness. The performance predicted by ANN agrees well with the experimental tests. In the dehumidifier, the maximum temperature and humidity ratio difference between the ANN model and experimental are 4% and 9%, respectively. While in the regenerator, the maximum difference is 4.6% and 10% respectively. An experimental setup has been carried out to evaluate the performance of the whole hybrid cooling system. Numerous definitions of coefficient of performance were used to represent the performance of the system and its components. As compared to a traditional air conditioning system, the hybrid air conditioning system improves the electrical COP and the total COP of the system by approximately 8.8% to 17% and 10.8% to 18.5%, respectively.,Ph.D. |
| Pages: | 201 |
| Call Number: | TP492.M834 2014 3 tesis |
| Publisher: | UKM, Bangi |
| Appears in Collections: | Solar Energy Research Institute / Institut Penyelidikan Tenaga Suria (SERI) |
Files in This Item:
| File | Description | Size | Format | |
|---|---|---|---|---|
| ukmvital_76240+Source01+Source010.PDF Restricted Access | 4.27 MB | Adobe PDF |  View/Open |
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