Effects of psyllium and cellulose fibres on thermal,structural, and in vitro digestion behaviour of wheat starch

The study investigated the effects of adding different types of fibre (psyllium and cellulose) on in vitro digestion behaviour of wheat starch with its thermal and structural properties. Psyllium and cellulose fibres interfered with the wheat starch differently. Psyllium fibre hindered starch gelatinisation, restricted the loss of starch crystallinity, and decreased the accessibility of enzymes to starch. In contrast, cellulose fibre had no significant effect on gelatinisation and loss of crystallinity but limited the digestive enzyme mobility. The impact of psyllium was more pronounced than cellulose on reducing starch digestibility. Rapidly digestible starch fractions of the cooked starch reduced from between 57.90 ± 0.60–69.72 ± 0.46 (% in starch) to between 28.06 ± 0.36–46.34 ± 1.10 (% in starch) and 53.23 ± 0.36–66.71 ± 0.24 (% in starch) for psyllium and cellulose fibre, respectively. This information could be helpful to design foods containing starch with reduced digestibility for a healthy diet.     

A tabu search approach for buffer allocation in production lines with unreliable machines

The optimal allocation of buffers is an important research issue in designing production lines. In this study, a tabu search (TS) algorithm is proposed to find near-optimal buffer allocation plans for a serial production line with unreliable machines. The main objective is to maximize the production rate, i.e. throughput, of the line. The efficiency of the proposed method is also tested to solve buffer allocation problems with the objective of total buffer size minimization. To estimate the throughput of the line with a given specific buffer allocation, an analytical decomposition approximation method is used. The performance of the tabu search algorithm is demonstrated on existing benchmark problems. The results obtained by the TS algorithm are clearly encouraging, as the TS algorithm is much better than the other algorithms for all considered benchmark problems.     

Effect of reference state on the performance of energy and exergy evaluation of geothermal district heating systems: Balcova example

In this paper, we undertake a parametric study to investigate how varying reference temperature from 0 to 25 °C will affect the energy and exergy efficiencies of the Balcova geothermal district heating system (BGDHS) and develop two significant correlations (with a correlation coefficient of 0.99) that can be used for predicting the efficiencies. The exergy losses in the overall BGDHS are quantified and illustrated using exergy flow diagram particularly for a reference temperature of 11.4 °C for comparison purposes. This reference temperature is taken as an average value of the ambient temperatures measured during the past 5 years for the day of 2nd January to reflect the actual situation. The results show that the exergy losses within the system occur mainly due to the losses in pumps, heat exchangers, reinjection sections of the geothermal water back into reservoir and pipeline, and account for 1.75%, 8.84%, 14.20%, and 28.69%, respectively. In addition, we study energy and exergy efficiencies to determine the possibilities to improve the system, and energy and exergy efficiencies of the system are found to be 42.36% and 46.55%, respectively, for 2nd January 2004.     

Thermodynamics and exergoeconomic analysis of geothermal power plants

Fossil fuel reserves (coal, oil, natural gas, etc.) diminish day by day. In addition, rapid advancement of technology causes an increase in the amount of energy needed. This emerging situation resulted in ever increasing importance of renewable energy sources, and various systems are being developed to utilize these renewable energy sources effectively.In this study, information about Ayd?n–Salavatli geothermal field’s features and working principles of the 2 power plants (DORA 1 and DORA 2) in the region are given. Power plants’ energy and exergy efficiencies were calculated with the emphasis on the effects of thermal fluids used in power plants. Also, in this study, some correlations were developed.Power plants’ sections which cause exergy losses were identified. Accordingly, improvement suggestions were presented in this study. Additionally, exergoeconomic analyses were conducted while power plants’ investment costs and equipment maintenance costs were taken into consideration.     

Exergetic assessment of EAHEs for building heating in Turkey: A greenhouse case study

The present study undertakes an exergy analysis of earth to air heat exchanger (EAHE) and applies to a local one in Turkey. Namely, the exergy performance of an EAHE has been evaluated in a demonstration in Solar Energy Institute of Ege University, Izmir, Turkey. Exergetic efficiencies of the system components are determined as an attempt to assess their individual performances. The daily maximum heating coefficient of performance (COP) value for the system is obtained to be 6.18. The total average COP in the experimental period is found to be 4.74.