Exergetic, exergoeconomic and exergoenvironmental analysis of intercooled gas turbine engine

Exergetic and exergoeconomic and exergoenvironmental analyses have been performed for an advanced aero-derivative intercooled gas turbine engine. The proposed system was modelled using the IPSEpro software package and validated using manufacturer’s published data. The exergoeconomic model evaluates the cost-effectiveness of the gas turbine engine based on the Specific Exergy Costing [SPECO] method. The CO2 emissions per KWh were estimated using a generic combustor model, HEPHAESTUS, developed at Cranfield University. It is well known that the exergetic analysis can determine the magnitudes, locations and types of losses within an energy system. The effect of load and ambient temperature variations on gas turbine performance were investigated for two different configurations. The first system, Case-I, was a simple gas turbine (SCGT) engine, and the second, Case-II, an intercooling gas turbine (ICGT) system. The latter enhances gas turbine efficiency but, at the same time, has an adverse effect on the combustion chamber due to reduced compressed air temperature. It was confirmed that full load and low ambient temperature are preferable due to the low waste exergy. The unit exergy cost rate for both SCGT and ICGT have been calculated as 8.59 and 8.32 US$/GJ respectively. The exergoenvironmental results show the ICGT achieved lower emission levels and is more environmentally friendly than the SCGT

Energetic and exergetic analysis of combined cycle power plant: Part-1 operation and performance

Energetic and exergetic analyses are conducted using operating data for Sabiya, a combined cycle power plant (CCPP) with an advanced triple pressure reheat heat recovery steam generator (HRSG). Furthermore, a sensitivity analysis is carried out on the HRSG using a recent approach to differentiate between the sources of irreversibility. The proposed system was modelled using the IPSEpro software and further validated by the manufacturer’s data. The performance of the Sabiya CCPP was examined for different climatic conditions, pressure ratios, pinch point temperatures, high-pressure steam, and condenser pressure values. The results confirmed that 60.9% of the total exergy destruction occurs in the combustion chamber, which constitutes the main source of irreversibilities within a system. The exergy destruction was significantly affected by both the pressure ratio and the high-pressure steam, where the relation between them was seen to be inversely proportional. The high-pressure stage contributes about 50% of the exergy destruction within the HRSG compared to other stages and the reheat system, due to the high temperature difference between the streams and the large number of components, which leads to high energy loss to the surroundings. Numerous possibilities for improving the CCPP’s performance are introduced, based on the obtained results

Exergetic and sustainability analysis of an intercooled gas turbine cogeneration plant with reverse osmosis desalination system

In this study, an advanced cogeneration plant based on a 100-MW aeroderivative intercooled gas turbine (ICGT) engine and large two-pass reverse osmosis (RO) desalination system is analyzed thermodynamically. The proposed model has been developed using specialized software and validated with manufacturers’ published data. Saline water is simulated using the latest physical properties available in the literature and treated as a real mixture. Combined energetic and exergetic performance criteria for the design of a cogeneration plant is presented as being, today, the most efficient method for accurate assessment of performance, which also permits quantification of system deficiencies. The performance of the proposed plant was investigated using different loads, ambient temperatures, pressure ratios, and feed water temperatures. The results show an intercooler system improves cogeneration plant performance despite having a negative impact on the combustion chamber performance because of its reduction of compressed air temperature. The ICGT engine is considered the best available choice to integrate with a RO unit because of its high pressure ratio and low power consumption in the compressors. From an operational perspective, full load and low ambient and high feed-water temperatures are highly recommended. The exergetic efficiency of the ICGT engine, RO system, and cogeneration plant are shown to be 44.3, 32.83, and 47.6%, respectively. From a sustainability perspective, the exergetic-environmental efficiency is slightly affected by ambient temperature, whereas it is highly affected by load variation. Based upon the obtained results, numerous possibilities are presented to improve the performance of cogeneration plants

A comparison of methods for assessing the thermal insulation value of children's schoolwear in Kuwait

In this study, three methods were used to determine the thermal insulation values of different school clothing worn by 6 to 17 year old girls and boys in Kuwait classrooms for both summer and winter seasons. The different clothing ensembles’ insulations were determined by 1: measurement using adultsized versions of the clothing on thermal manikins, 2: estimations from adult clothing data obtained from the standards tables in ISO 9920 and ASHRAE 55, and 3: calculations using a regression equation from McCullough et al. (1985) that was adapted to accommodate children’s sizes for ages 6e17 years. Values for the clothing area factor, fcl, were also determined by measurement and by using a prediction equation from ISO 9920. Results in this study suggested that the clothing insulation values found from the measured and adapted data were similar to the adult’s data in standards tables for the same summer and winter seasons. Further, the effect of the insulation values on the different scholars’ age groups were investigated using the clothing temperature rating technique and compared to the scholars’ comfort temperature found in recent field studies. Results showed that the temperature ratings of the clothing using the three methods described above are close and in agreement with the scholars’ comfort temperature. Though estimated and measured fcl data differed, the impact on the temperature ratings was limited. An observed secular change in the children’s heights and weights in the last few decades implies that, for adolescents, the children’s body surface areas are similar to those of adults, making the use of adult clothing tables even more acceptable. In conclusion, this study gives some evidence to support the applicability of using adults’ data in ASHRAE 55 and ISO 9920 standards to assess the thermal insulation values of different children’s clothing ensembles, provided that careful selection of the garments, ensembles material and design takes place