Please use this identifier to cite or link to this item: http://scholarbank.nus.edu.sg/handle/10635/31603
Title: EXPERIMENTAL AND THEORETICAL STUDIES OF A CO-GENERATION SYSTEM FOR AN INDUSTRIAL PLANT
Authors: AUNG MYAT
Keywords: Co-generation, minimization of entropy generation, energy efficiency, adsorption, absorption, Thermally activated system
Issue Date: 9-Nov-2011
Source: AUNG MYAT (2011-11-09). EXPERIMENTAL AND THEORETICAL STUDIES OF A CO-GENERATION SYSTEM FOR AN INDUSTRIAL PLANT. ScholarBank@NUS Repository.
Abstract: This thesis presents the theoretical and experimental investigation of the co-generation system that produces simultaneously four types of useful energy namely: (i) electricity, (ii) steam, (iii) cooling and (iv) dehumidification. The co-generation plant comprises a Capstone C30 micro-turbine, which generates 24 kW of electricity, a compact and efficient waste heat recovery system, and a host of waste heat activated devices namely (i) a steam generator, (ii) an absorption chiller, (iii) an adsorption chiller and (iv) a multi-bed desiccant dehumidifier. The theoretical study modelled the mass and energy conservation of the above mentioned waste heat activated devices using the governing equations developed based on thermodynamic property fields of adsorbent-adsorbate systems such as the internal energy, the enthalpy, the specific heat capacity and the entropy as a function of pressure (P), temperature (T) and amount of adsorbate (q). Based on a lumped-parameter approach, the model is solved using the FORTRAN-based International Mathematics and Statistics Library (IMSL) Libraries. The co-generation system studied here is a temperature cascaded configuration of the exhaust gas emanating from the Capstone C 30 micro-turbine in order to maximize the energy recovery from the exhaust gas. The performance investigation of each of the devices in TCCP plant was performed at different heat source temperatures. It was observed that the optimal activation temperature of exhaust gas for the steam generator was about 285°C while the optimal firing temperatures for the absorption chiller, the adsorption chiller and the multi-bed desiccant dehumidification system were achieved 90°C, 82°C and 77 °C, respectively. The entropy generation analysis determines the amount of dissipation in a specific heat and mass transfer process within the thermodynamic cycle. All real processes are irreversible with entropy generation from friction, heat transfer and mass transfer. In contrast to energy, entropy generation is a measure of the system dissipation or lost work. The entropy generation analysis was carried out using the Gibbs free energy approach. In the analysis, it was found that the system total entropy generation was increased with increase in the heat source activation temperature. Thus, the author introduced the specific entropy generation which is the ratio of system entropy generation and the energy produced from the system. Genetics Algorithm, which produces the global minima rather than the local minima, was introduced to optimize both operational conditions such as coolant flow rates, heating fluid flow rates and the configuration of the area of heat transfer of the heat exchangers so as to reduce the specific entropy generation. The minimization of the specific entropy generation of the co-generation plant along with GA tool was performed. It is found out that the optimal firring temperature of each of the waste heat activated devices tends to decrease with the number of cascaded waste heat recovery heat exchanger is increased. Therefore, it is observed that temperature cascaded configuration for the waste heat recovery system could achieve the different hot water temperature for different waste heat activated devices. It was found out that the optimal energy utilization factor (EUF) for the co-generation plant is about 70% while the specific entropy generation is minimal.
URI: http://scholarbank.nus.edu.sg/handle/10635/31603
Appears in Collections:Ph.D Theses (Open)

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