A study on hydrophobic membrane for dehumidification | |
| Author | Ekkapharb Sriussadaporn |
| Call Number | AIT Thesis no. ET-02-20 |
| Subject(s) | Humidity--Control Membranes (Technology) |
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering. School of Environment Resources, and Development |
| Publisher | Asian Institute of Technology |
| Series Statement | Thesis ; no. ET-02-20 |
| Abstract | Incorporating desiccant in air-conditioning systems to handle the latent load will help reduce electricity consumption. Although, solid desiccant is more widely used, liquid desiccant has more potential to save electricity. However, the most important issue for conventional equipments, i.e. packed tower, tray column and spray tower that bring an intimate contact between liquid desiccant and moist air for dehumidification is the carryover of liquid droplet. The use of hydrophobic membrane which acts as a barrier between the two phases can be another approach to overcome this problem. The device that employs the hydrophobic membrane is known as a membrane contactor. Besides an elimination of the carryover, the membrane contactor could provide better dehumidification performance due to substantially higher surface area per unit volume. Those advantages of the membrane contactor make it become attractive. This study theoretically investigates the application of membrane contactor for dehumidification. The model of a prototype membrane contactor proposed by Bergem and Chiari was developed by using an analogy with conventional cross-flow heat exchanger. The set of equations contained in this model were solved by using Engineering Equation Solver (EES) Program. Two liquid desiccants, lithium chloride and lithium bromide were used for the analysis. Lithium chloride was used for the comparison of humidity reduction computed by the model with that from the experimental result in literature and the model developed by finite-volume technique. The comparison indicated that through the finite-volume model has better accuracy, this model yields satisfactory result. This demonstrates the feasibility to use the simpler model developed from an analogy with a conventional cross-flow heat exchanger for predicting the pe1formance of a membrane contactor for dehumidification. Lithium bromide was used to investigate the influence of solution inlet temperature, solution inlet concentration, air flow rate and a number of rows on rate of water vapor absorption, air outlet and inlet temperature difference, solution outlet and inlet temperature difference and air outlet and inlet specific enthalpy difference. The assessment on the capability of membrane contactor using lithium bromide to handle the latent load of air-conditioning system were also carried out in this study by using result from the model. The assessment indicated that two membrane contactors are needed to provide sufficient humidity reduction for one occupant at moderately active office work in Thai climate. In addition, the results obtained from the model of the contactor using lithium bromide were used for the comparison of membrane contactor's capacity with that of a conventional contactor, i.e. a packed tower. This comparison found that, at the same volume, the capacity of the membrane contactor is inferior to the conventional packed tower. However, improving the capacity is possible because this prototype contactor has lower surface area per unit volume than typical values |
| Year | 2002 |
| Corresponding Series Added Entry | Asian Institute of Technology. Thesis ; no. ET-02-20 |
| Type | Thesis |
| School | School of Environment, Resources, and Development (SERD) |
| Department | Department of Energy and Climate Change (Former title: Department of Energy, Environment, and Climate Change (DEECC)) |
| Academic Program/FoS | Energy Technology (ET) |
| Chairperson(s) | Kumar, S.; |
| Examination Committee(s) | Bhattacharya, S.C. ;Surapong Chirarattananon ; |
| Scholarship Donor(s) | Asian Institute of Technology (Partial Scholarship) |
| Degree | Thesis (M.Eng.) - Asian Institute of Technology, 2002 |