Exergy Analysis of Southern Negros Geothermal Field, Philippines

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dc.contributor.advisor Kaya, Eylem en
dc.contributor.advisor Zarrouk, Sadiq J. en
dc.contributor.author Bacus, Kathrina A. en
dc.date.accessioned 2020-08-18T21:42:55Z en
dc.date.issued 2020 en
dc.identifier.uri http://hdl.handle.net/2292/52668 en
dc.description Full Text is available to authenticated members of The University of Auckland only. en
dc.description.abstract Exergy analysis is important for quantifying the performance, identifying the sources/causes of inefficiency, and for determining options for optimising the output of a thermal process (Szargut et al., 1988). In a geothermal power plant, the performance is commonly measured through the second law (exergy/utilisation) efficiency (surface) of the process. It is usually obtained from the ratio between the net generated electrical power and the exergetic power from the produced geothermal fluids at the wellheads. This means that exergy analysis is only conducted at the surface level (ground) of the system and does not take into account the sub-surface reservoir, making the optimisation options limited. This work aims to perform a holistic (surface and sub-surface) exergy analysis of the Southern Negros Geothermal Production (SNGP) field. Exergy at the surface was calculated using the identified fluid properties at different components of the power plant. Meanwhile, exergy at the sub-surface was analysed using the modified AUTOUGH2 numerical reservoir model. Based on the results, the standard utilisation efficiency (surface) of SNGP field is 40.5%. This is comparable to 39.9 % (Aqui et al., 2005), which was referred to the exergy of the fluid at the production wellhead. However, it was more appropriate to measure the power plant performance through the overall utilisation efficiency (surface and reservoir), i.e. 34.51%. This is because the reservoir is an integral part of the energy conversion process for steam/power production. Any changes at the surface parameters will consider the impact to the reservoir, which is the heat source for producing work. An optimisation assessment was carried out to determine the field’s optimum overall utilisation efficiency at varying separator pressure. Results produced the optimum brine reinjection temperature of 140 ºC. This value was nearly the same as the results at the existing brine reinjection temperature of 165 ºC. Thus, if the existing separator pressure will be decreased to the optimal setting, the performance of the geothermal system is most favourable. Considering that reservoir pressure reduces as mass extraction continues over time, decreasing the separator pressure allows more low-pressure highii enthalpy operating production wells to sustain production and maintain the steam supply to the power plant. en
dc.publisher ResearchSpace@Auckland en
dc.relation.ispartof Masters Thesis - University of Auckland en
dc.relation.isreferencedby UoA99265321713802091 en
dc.rights Items in ResearchSpace are protected by copyright, with all rights reserved, unless otherwise indicated. Previously published items are made available in accordance with the copyright policy of the publisher. en
dc.rights Restricted Item. Full Text is available to authenticated members of The University of Auckland only. en
dc.rights.uri https://researchspace.auckland.ac.nz/docs/uoa-docs/rights.htm en
dc.rights.uri http://creativecommons.org/licenses/by-nc-sa/3.0/nz/ en
dc.title Exergy Analysis of Southern Negros Geothermal Field, Philippines en
dc.type Thesis en
thesis.degree.discipline Engineering Science en
thesis.degree.grantor The University of Auckland en
thesis.degree.level Masters en
dc.rights.holder Copyright: The author en
pubs.elements-id 810544 en
pubs.record-created-at-source-date 2020-08-19 en


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