Browsing by Author "Khattak, Sanober"

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    Analysing the use of waste factory heat through exergy analysis
    (2014) Khattak, Sanober; Greenough, R. M.; Brown, Neil
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    Exergy analysis of a four pan jaggery making process
    (Elsevier, 2018-08-02) Khattak, Sanober; Sardeshpande, V.; Brown, Neil; Greenough, R. M.
    Jaggery is a non-traditional sweetener that is produced from boiling sugarcane juice. Due to the energy intensive nature of the combustion process in jaggery making, previous studies in literature have presented various process and equipment modifications to affect its energy efficiency. This study adds to the understanding of the resource transformations and consumptions in the jaggery process by presenting its exergy analysis. The baseline process was operationally modified for which the exergy efficiency and exergy destruction are calculated. Through the modifications, the exergy efficiency and exergy destruction increased by 11.2% and 0.8% respectively. A significant amount of exergy was wasted as surplus heat in the form of flue gas, which reduced by 11.5% due to process modifications. The results show that while the most evident form of resource waste was due to flue gas released into the environment, the largest form of resource consumption was actually due to exergy destruction arising from irreversibilities in combustion, a result not clearly evident through energy analysis alone. Through modelling process flows in terms of exergy, the analysis presented in this paper increases the visibility of the resource consumptions and losses in the jaggery making process. This study should aid the efforts of researchers and practitioners aiming to reduce resource consumption in the jaggery making process.
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    An exergy based approach to resource accounting for factories
    (Elsevier, 2015-12-31) Khattak, Sanober; Greenough, R. M.; Korolija, Ivan; Brown, Neil
    Resource accounting is widely practiced to identify opportunities for improving the sustainability of industrial systems. This paper presents a conceptual method for resource accounting in factories that is based on the fundamentals of thermodynamics. The approach uses exergy analysis and treats the factory as an integrated energy system comprising a building, its technical building services and manufacturing processes. The method is illustrated with a case study of an automotive cylinder head manufacturing line in which the resource efficiency of this part of the factory is analysed for different energy system options relating to heating ventilation and air conditioning. Firstly, the baseline is compared with the use of a solar photovoltaic array to generate electricity, and then a heat recovery unit is considered. Finally, both of these options are used together, and here it was found that the non-renewable exergy supply and exergy destruction are reduced by 51.6% and 49.2% respectively. Also, it was found that a conventional energy analysis would overestimate the resource savings from reducing the hot water supplied to the heating system, since energy analysis cannot account for energy quality. Since exergy analysis accounts for both energy quality and quantity it produces a different result. The scientific value of this paper is that it presents an exergy-based approach for factory resource accounting, which is illustrated through application to a real factory. The exergy-based approach is shown to be a valuable complement to energy analysis, which could lead to a more resource efficient system design than one based on energy analysis alone.
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    An exergy based method for resource accounting in factories
    (De Montfort University, 2016-01) Khattak, Sanober
    In the current global climate of declining fossil fuel reserves and due to the impact of industry on the natural environment, industrial sustainability is becoming ever more important. However, sustainability is quite a vague concept for many, and there are a range of interpretations of the word. If the resource efficiency of a factory is taken as a measure of its sustainability, then the concept becomes better defined and quantifiable. In order to analyse the resource efficiency of a factory and suggest improvements, all flows through the manufacturing system need to be modelled. However the factory is a complex environment, there is a wide variation in the quality levels of energy as well as the composition of material flows in the system. The research presented in this thesis shows how the thermodynamics-based concept of ‘exergy’ can be used to quantify the resource efficiency of a factory. The factory is considered an ‘integrated system’, meaning it is composed of the building and the production processes, both interacting with each other. This is supported by three case studies in different industries that demonstrate the practical application of the approach. A review of literature identified that it was appropriate to develop a novel approach that combined exergy analysis with the integrated view of the factory. Such an approach would allow a ‘holistic’ assessment of resource efficiency for different technology options possibly employable. The development of the approach and its illustration through practical case studies is the main contribution of the work presented. Three case studies, when viewed together, illustrate all aspects of the novel exergy based resource accounting approach. The first case study is that of an engine production line, in which the resource efficiency of this part of the factory is analysed for different energy system options relating to heating ventilation and air conditioning. Firstly, the baseline is compared with the use of a solar photovoltaic array to generate electricity, and then a heat recovery unit is considered. Finally, both of these options were used together, and here it is found that the non-renewable exergy supply and exergy destruction are reduced by 51.6% and 49.2% respectively. The second case study is that of a jaggery (a sugar substitute) production line. The exergy efficiency of the process is calculated based on varying the operating temperature of the jaggery furnace. The case study describes the modelling of al flows through the jaggery process in terms of exergy. Since this is the first example of an exergy analysis of a jaggery process, it can be considered a minor contribution of the work. An imaginary secondary process that could utilize the waste heat from the jaggery process is considered in order to illustrate the application of the approach to industrial symbiosis. The non-renewable exergy supply and exergy destruction are determined for the baseline and the alternative option. The goal of this case study is not to present a thermally optimized design; rather it illustrates how the exergy concept can be used to assess the impact of changes to individual process operations on the overall efficiency in industrial symbiosis. When considering natural resource consumption in manufacturing, accounting for clean water consumption is increasingly important. Therefore, a holistic methodology for resource accounting in factories must be able to account for water efficiency as well. The third case study is that of a food production facility where the water supply and effluent are modelled in terms of exergy. A review of relevant literature shows that previously, the exergy content of only natural water bodies and urban wastewater had been quantified. To the author’s knowledge, this is the first example of applying this methodology of modelling water flows in a manufacturing context. The results show that due to a high amount of organic content in food process effluent, there is significant recoverable exergy in it. Therefore, a hypothetical water treatment process was assumed to estimate the possible savings in exergy consumption. The results show that at least a net 4.1% savings in terms of exergy could be possible if anaerobic digestion water treatment was employed. This result can be significant for the UK since the food sector forms a significant portion of the industry in the country. Towards the end of the thesis, a qualitative study is also presented that aims to evaluate the practical utility of the approach for the industry. A mixed method approach was used to acquire data from experts in the field and analyse their responses. The exergy based resource accounting method developed in this thesis was first presented to them before acquiring the responses. A unanimous view emerged that the developed exergy based factory resource accounting methodology has good potential to benefit industrial sustainability. However, they also agreed that exergy was too complex a concept to be currently widely applied in practice. To this effect, measures that could help overcome this barrier to its practical application were presented which form part of future work.
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    Flexible future comfort
    (Routledge, 2022-04-19) Khattak, Sanober; Wright, A. J.; Natarajan, Sukumar
    Cooling is the fastest growing user of energy in buildings, and predicted to triple globally by 2050, driven not least by demand from hot countries such as India. This single trend has already had, and increasingly will have significant consequences around the world, driving up carbon emissions, energy insecurity and triggering blackouts. Mechanically cooled buildings are typically designed using international comfort standards, like ASHRAE 55, that mandate a static indoor environment (typically 23 ± 2°C) leading to unnecessarily high energy use. The impacts of a more flexible approach to comfort are considered here, involving a more active role for occupants. This flexible approach is described, and tested, using a simulation-based case study of a typical residential apartment in India. Compared to a fixed setpoint of 24°C, the flexible comfort approach results in reduced peak load and total cooling demand by 20% and 41%, respectively, at the cost of slightly elevated discomfort (average 12% PPD). The study demonstrates how this flexible comfort approach can be both thermally comfortable and more energy-efficient in mechanically cooled buildings, under extreme summer conditions. Finally, ways in which comfort in buildings might evolve are discussed, regarding changes in climate, work practices, cities, energy and transport.
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    Keeping Cool in the Desert: Using Wind Catchers for Improved Thermal Comfort and Indoor Air Quality at Half the Energy
    (MDPI, 2021-03-06) Saif, Jamal; Wright, A. J.; Khattak, Sanober; Elfadli, Kasem
    In hot arid climates, air conditioning in the summer dominates energy use in buildings. In Kuwait, energy demand in buildings is dominated by cooling, which also determines the national peak electricity demand. Schools contribute significantly to cooling demand, but also suffer from poor ventilation. This paper presents analysis of a ventilation and cooling system for school classrooms using a wind catcher for natural ventilation and evaporative cooling. A school classroom in Kuwait with single-sided ventilation was modelled using the DesignBuilder V5.4/EnergyPlus V9.1 software and calibrated using field data. The model was used to analyse the performance of a wind catcher, with and without evaporative cooling, in terms of energy use, thermal comfort and indoor air quality. Compared to the baseline of using air-conditioning only, a wind catcher with evaporative cooling was found to reduce energy use by 52% during the summer months while increasing the comfortable hours from 76% to 100% without any supplementary air conditioning. While the time below the ASHRAE CO2 limit also improved from 11% to 24% with the wind catcher, the indoor air quality was still poor. These improvements came at the cost of a 14% increase in relative humidity. As the wind catcher solution appears to have potential with further development; several avenues for further research are proposed.
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    Potential Economic Benefits of Carbon Dioxide (CO2) Reduction Due to Renewable Energy and Electrolytic Hydrogen Fuel deployment under current and Long Term Forecasting of the Social Carbon Cost (SCC)
    (Elsevier, 2019-05-23) Rahil, Abdullah; Gammon, Rupert; Brown, Neil; Udie, Justin; Akram, Muhammad Usman; Khattak, Sanober
    The 2016 Paris Agreement (UNFCCC Authors, 2015) is the latest of initiative to create an international consensus on action to reduce GHG emissions. However, the challenge of meeting its targets lies mainly in the intimate relationship between GHG emissions and energy production, which in turn links to industry and economic growth. The Middle East and North African region (MENA), particularly those nations rich oil and gas (O&G) resources, depend on these as a main income source. Persuading the region to cut down on O&G production or reduce its GHG emissions is hugely challenging, as it is so vital to its economic strength. In this paper, an alternative option is established by creating an economic link between GHG emissions, measured as their CO2 equivalent (CO2e), and the earning of profits through the concept of Social Carbon Cost (SCC). The case study is a small coastal city in Libya where 6% of electricity is assumed to be generated from renewable sources. At times when renewable energy (RE) output exceeds the demand for power, the surplus is used for powering the production of hydrogen by electrolysis, thus storing the energy and creating an emission-free fuel. Two scenarios are tested based on short and long term SCCs. In the short term scenario, the amount of fossil fuel energy saved matches the renewable energy produced, which equates to the same amount of curtailed O&G production. The O&G-producing region can earn profits in two ways: (1) by cutting down CO2 emissions as a result of a reduction in O&G production and (2) by replacing an amount of fossil fuel with electrolytically-produced hydrogen which creates no CO2 emissions. In the short term scenario, the value of SCC saved is nearly 39% and in the long term scenario, this rose to 83%.
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    Precursors to using energy data as a manufacturing process variable
    (IEEE, 2012) Greenough, R. M.; Vikhorev, K.; Brown, Neil; Khattak, Sanober
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    Resource Accounting in Factories and the Energy-Water Nexus
    (Springer, 2017-10-11) Khattak, Sanober; Greenough, R. M.
    A manufacturing system comprises production processes and building services, both of which are supplied by different energy carriers as well as raw materials and water. These resources interact according to complex relationships and are converted into products for sale and waste flows. Holistic resource accounting allows the analyst to consider the dynamic relationships between these components, including the strong interdependence between energy and water, which has been called the energy-water nexus. Exergy analysis is a method that accounts for mass and both the quantity and quality of energy, while allowing analysis on a common basis and for this reason it is used increasingly to analyse resource consumption in manufacturing systems; however it has rarely been used to consider water flows alongside energy and material flows. The main contribution of this paper is the presentation of modeling water flows in terms of exergy in the context of sustainable manufacturing. Using this technique in combination with previously developed exergy based methods; the result is a truly holistic resource accounting method for factories based on exergy analysis that incorporates water flows. The method is illustrated using a case study of a food factory in which a 4.1% reduction in resource use is shown to be possible by employing anaerobic digester in an effluent water treatment process. The benefits of this technology option would have been underestimated compared to the benefits of waste heat capture if an analysis based on mass and energy balances alone had been used. The scientific value of this paper is the demonstration of the relatively high exergy content of effluent flows, which should therefore be regarded as potentially valuable resources. The analytical method presented is therefore of value to a wide range of industries beyond the food industry.
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    A review on BIPV-induced temperature effects on urban heat islands
    (Elsevier, 2023-06-28) Elhabodi, Tarek S.; Yang, Siliang; Parker, James; Khattak, Sanober; He, Bao-Jie; Attia, Shady
    Urban Heat Islands (UHI) occur in and around cities, leading to warmer temperatures than in surrounding rural areas. The UHI effect increases energy demand, air pollution levels, and heat-related illness and mortality. Solar energy is one of the most widely adopted renewable energy generation technologies in the built environment. Solar photovoltaic (PV) systems, integrated into building envelopes, can form a cohesive design, construction and energy solution for buildings, namely, building-integrated photovoltaic system (BIPV). However, the BIPV panels might potentially exacerbate the UHI intensity by trapping more heat in urban areas. This review paper uses a detailed literature survey of over 100 sources to evaluate whether the uptake of BIPV systems in urban areas contributes to an aggravation of the UHI effect. The survey found both direct and indirect impacts of BIPV systems on UHI, which also identified the fundamental causes of UHI such as the albedo effect and heat dispersion and how this would be embodied in the BIPV installations. Furthermore, this paper discusses how to mitigate the impact of BIPV systems on the UHI, as well as the future research directions around this concern in relation to the urban design.
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    Software Engineering for Building Energy Efficiency
    (2014) Brown, Neil; Snape, J. Richard; Khattak, Sanober; Greenough, R. M.
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    Thermodynamic Performance Analysis of High Thermal Conductivity Materials in Borehole Heat Exchangers in the European Climate
    (MDPI, 2023-09-07) Khattak, Sanober; Badenes, Borja; Urchueguia, Javier; sanner, barkhard
    While heat pumps have been acknowledged as a key enabling technology to achieve Net Zero goals, their uptake is limited by their performance and cost. In this paper, a simulation-based study is conducted to analyse the performance of ground source heat pumps (GSHPs) utilising high thermal conductivity materials for the borehole heat exchanger (BHE) pipe (1 W/mK) and grouting (3 W/mK) developed in the GEOCOND project. Exergy analysis is conducted to account for energy quantity and quality with a focus on BHE performance. An annual hourly simulation was performed using DesignBuilder V5.4 and Earth Energy Designer (EED4) for representative cool and hot locations in Europe—Stockholm and Valencia, respectively. For a constant BHE length, the results for Stockholm show that the high conductivity materials result in an increase of about 13% BHE exergy extraction compared to the standard grout and pipe, but no such improvement was observed for Valencia. The difference between outdoor temperature and its dynamic variation from the indoor setpoint is identified as a key factor in the overall GSHP exergetic performance. In future research, we propose a thorough life cycle analysis across diverse locations and varying indoor comfort criteria to pinpoint areas where the high thermal conductivity material can enable cost-effective, sustainable heating and cooling.
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    Towards improved energy and resource management in manufacturing
    (MDPI, 2018-04) Khattak, Sanober; Oates, Michael; Greenough, R. M.
    Exergy analysis has widely been used to assess resource consumption, and to identify opportunities for improvement within manufacturing. The main advantages being its ability to account for energy quality and consumption. However, its application in industrial practice is limited, which may be due to the lack of its consistent application in practice. Current energy management standards, that facilitate consistent application of procedures, do not consider the quality aspects of energy flows. An exergy based energy management standards is proposed in this paper that would take into account energy quality aspects, while facilitating the consistent application of exergy analysis in industrial practice. Building on ISO50001, this paper presents guidelines for implementing energy and resource management in factories, incorporating the concepts of exergy and holistic factory simulation, illustrated through a manufacturing case study. From the factory level analysis, a chilling process was identified to have significant improvement potential. A dry fan cooler, using ambient air was proposed for improved efficiency of the chillers. Energy based metrics portrayed a system that operated at high efficiency, however exergy analysis indicated much room for further improvement, therefore impacting decision making for technology selection. The contribution of this paper is in presenting a set of prescriptive guidelines that could possibly be further developed into a new energy management standard that would utilize the advantages of exergy analysis towards improved energy and resource management in manufacturing.