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Dr. Fahid Riaz
National University of Singapore

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Short Biography

Dr Fahid Riaz has completed his PhD in Mechanical Engineering with specialization in Sustainable Energy Systems from National University of Singapore (NUS) under full scholarship from NUS. He holds double Masters degrees from KTH Sweden and TU Eindhoven Netherlands. He was recipient of the prestigious ERASMUS MUNDUS Scholarship from EU for his Master studies. He obtained his BSc Mechanical Engineering (with honours, Dean's list) from UET Lahore Pakistan. He has working experience in industry and academia and also is involved in research commercialization and entrepreneurial activities. His is interested in renewable energy technologies, waste heat recovery, refrigeration and air-conditioning, power plants, Thermo-fluids engineering, sustainability, and, R&D and innovation management.

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Journal article
Published: 20 August 2021 in Sustainability
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The prevailing massive exploitation of conventional fuels has staked the energy accessibility to future generations. The gloomy peril of inflated demand and depleting fuel reservoirs in the energy sector has supposedly instigated the urgent need for reliable alternative fuels. These very issues have been addressed by introducing oxyhydrogen gas (HHO) in compression ignition (CI) engines in various flow rates with diesel for assessing brake-specific fuel consumption (BSFC) and brake thermal efficiency (BTE). The enrichment of neat diesel fuel with 10 dm3/min of HHO resulted in the most substantial decrease in BSFC and improved BTE at all test speeds in the range of 1000–2200 rpm. Moreover, an Artificial Intelligence (AI) approach was employed for designing an ANN performance-predicting model with an engine operating on HHO. The correlation coefficients (R) of BSFC and BTE given by the ANN predicting model were 0.99764 and 0.99902, respectively. The mean root errors (MRE) of both parameters (BSFC and BTE) were within the range of 1–3% while the root mean square errors (RMSE) were 0.0122 kg/kWh and 0.2768% for BSFC and BTE, respectively. In addition, ANN was coupled with the response surface methodology (RSM) technique for comprehending the individual impact of design parameters and their statistical interactions governing the output parameters. The R2 values of RSM responses (BSFC and BTE) were near to 1 and MRE values were within the designated range. The comparative evaluation of ANN and RSM predicting models revealed that MRE and RMSE of RSM models are also well within the desired range but to be outrightly accurate and precise, the choice of ANN should be potentially endorsed. Thus, the combined use of ANN and RSM could be used effectively for reliable predictions and effective study of statistical interactions.

ACS Style

Muhammad Usman; Haris Hussain; Fahid Riaz; Muneeb Irshad; Rehmat Bashir; Muhammad Haris Shah; Adeel Ahmad Zafar; Usman Bashir; M. A. Kalam; M. A. Mujtaba; Manzoore Elahi M. Soudagar. Artificial Neural Network Led Optimization of Oxyhydrogen Hybridized Diesel Operated Engine. Sustainability 2021, 13, 9373 .

AMA Style

Muhammad Usman, Haris Hussain, Fahid Riaz, Muneeb Irshad, Rehmat Bashir, Muhammad Haris Shah, Adeel Ahmad Zafar, Usman Bashir, M. A. Kalam, M. A. Mujtaba, Manzoore Elahi M. Soudagar. Artificial Neural Network Led Optimization of Oxyhydrogen Hybridized Diesel Operated Engine. Sustainability. 2021; 13 (16):9373.

Chicago/Turabian Style

Muhammad Usman; Haris Hussain; Fahid Riaz; Muneeb Irshad; Rehmat Bashir; Muhammad Haris Shah; Adeel Ahmad Zafar; Usman Bashir; M. A. Kalam; M. A. Mujtaba; Manzoore Elahi M. Soudagar. 2021. "Artificial Neural Network Led Optimization of Oxyhydrogen Hybridized Diesel Operated Engine." Sustainability 13, no. 16: 9373.

Journal article
Published: 13 August 2021 in Alexandria Engineering Journal
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The vibrations of bearings holding the high-speed shaft of a steam turbine are critically controlled for the safe and reliable power generation at the power plants. In this paper, two artificial intelligence (AI) process models, i.e., artificial neural network (ANN) and support vector machine (SVM) based relative vibration modeling of a steam turbine shaft bearing of a 660 MW supercritical steam turbine system is presented. After extensive data processing and machine learning based visualization tests performed on the raw operational data, ANN and SVM models are trained, validated and compared by external validation tests. ANN has outperformed SVM in terms of better prediction capability and is, therefore, deployed for simulating the constructed operating scenarios. ANN process model is tested for the complete load range of power plant, i.e., from 353 MW to 662 MW and 4.07% reduction in the relative vibration of the bearing is predicted by the network. Further, various vibration reduction operating strategies are developed and tested on the validated and robust ANN process model. A selected operating strategy which has predicted a promising reduction in the relative vibration of bearing is selected. In order to confirm the effectiveness of the prediction of the ANN process model, the selected operating strategy is implemented on the actual operation of the power plant. The resulting reduction in the relative vibrations of the turbine’s bearing, which is less than the alarm limit, are confirmed. This cements the role of ANN process model to be used as an operational excellence tool resulting in vibration reduction of high-speed rotating equipment.

ACS Style

Waqar Muhammad Ashraf; Yasir Rafique; Ghulam Moeen Uddin; Fahid Riaz; Muhammad Asim; Muhammad Farooq; Abid Hussain; Chaudhary Awais Salman. Artificial intelligence based operational strategy development and implementation for vibration reduction of a supercritical steam turbine shaft bearing. Alexandria Engineering Journal 2021, 1 .

AMA Style

Waqar Muhammad Ashraf, Yasir Rafique, Ghulam Moeen Uddin, Fahid Riaz, Muhammad Asim, Muhammad Farooq, Abid Hussain, Chaudhary Awais Salman. Artificial intelligence based operational strategy development and implementation for vibration reduction of a supercritical steam turbine shaft bearing. Alexandria Engineering Journal. 2021; ():1.

Chicago/Turabian Style

Waqar Muhammad Ashraf; Yasir Rafique; Ghulam Moeen Uddin; Fahid Riaz; Muhammad Asim; Muhammad Farooq; Abid Hussain; Chaudhary Awais Salman. 2021. "Artificial intelligence based operational strategy development and implementation for vibration reduction of a supercritical steam turbine shaft bearing." Alexandria Engineering Journal , no. : 1.

Journal article
Published: 01 August 2021 in Processes
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In this study, the response surface methodology (RSM) optimization technique was employed for investigating the impact of hydroxy gas (HHO) enriched diesel on performance, acoustics, smoke and exhaust gas emissions of the compression ignition (CI) engine. The engine was operated within the HHO flow rate range of 0–10 L/min and engine loads of 15%, 30%, 45%, 60% and 75%. The results disclosed that HHO concentration and engine load had a substantial influence on the response variables. Analysis of variance (ANOVA) results of developed quadratic models indicated the appropriate fit for all models. Moreover, the optimization of the user-defined historical design of an experiment identified an optimum HHO flow rate of 8 L/min and 41% engine load, with composite desirability of 0.733. The responses corresponding to optimal study factors were 25.44%, 0.315 kg/kWh, 117.73 ppm, 140.87 ppm, 99.37 dB, and 1.97% for brake thermal efficiency (BTE), brake specific fuel consumption (BSFC), CO, HC, noise, and smoke, respectively. The absolute percentage errors (APEs) of RSM were predicted and experimental results were below 5%, which vouched for the reliable use of RSM for the prediction and optimization of acoustics and smoke and exhaust emission characteristics along with the performance of a CI engine.

ACS Style

Muhammad Usman; Saifuddin Nomanbhay; Mei Ong; Muhammad Saleem; Muneeb Irshad; Zain Hassan; Fahid Riaz; Muhammad Shah; Muhammad Qyyum; Moonyong Lee; Pau Show. Response Surface Methodology Routed Optimization of Performance of Hydroxy Gas Enriched Diesel Fuel in Compression Ignition Engines. Processes 2021, 9, 1355 .

AMA Style

Muhammad Usman, Saifuddin Nomanbhay, Mei Ong, Muhammad Saleem, Muneeb Irshad, Zain Hassan, Fahid Riaz, Muhammad Shah, Muhammad Qyyum, Moonyong Lee, Pau Show. Response Surface Methodology Routed Optimization of Performance of Hydroxy Gas Enriched Diesel Fuel in Compression Ignition Engines. Processes. 2021; 9 (8):1355.

Chicago/Turabian Style

Muhammad Usman; Saifuddin Nomanbhay; Mei Ong; Muhammad Saleem; Muneeb Irshad; Zain Hassan; Fahid Riaz; Muhammad Shah; Muhammad Qyyum; Moonyong Lee; Pau Show. 2021. "Response Surface Methodology Routed Optimization of Performance of Hydroxy Gas Enriched Diesel Fuel in Compression Ignition Engines." Processes 9, no. 8: 1355.

Journal article
Published: 19 May 2021 in Energies
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The protection of the environment and pollution control are issues of paramount importance. Researchers today are engrossed in mitigating the harmful impacts of petroleum waste on the environment. Lubricating oils, which are essential for the smooth operation of engines, are often disposed of improperly after completing their life. In the experimental work presented in this paper, deteriorated engine oil was regenerated using the acid treatment method and was reused in the engine. The comparison of the properties of reused oil, the engine’s performance, and the emissions from the engine are presented. The reuse of regenerated oil, the evaluation of performance, and emissions establish the usefulness of the regeneration of waste lubricating oil. For the used oil, total acid number (TAN), specific gravity, flash point, ash content, and kinematic viscosity changed by 60.7%, 6.7%, 4.4%, 96%, and 15.5%, respectively, compared with fresh oil. The regeneration partially restored all the lost lubricating oil properties. The performance parameters, brake power (BP), brake specific fuel consumption (BSFC), and exhaust gas temperature (EGT) improved with regenerated oil in use compared with used oil. The emissions CO and NOX contents for acid-treated oil were 9.7% and 17.3% less in comparison with used oil, respectively. Thus, regenerated oil showed improved performance and oil properties along with significantly reduced emissions when employed in an SI engine.

ACS Style

Muhammad Usman; Muhammad Jamil; Fahid Riaz; Haris Hussain; Ghulam Hussain; Muhammad Shah; Muhammad Qyyum; Chaudhary Salman; Moonyong Lee. Refining and Reuse of Waste Lube Oil in SI Engines: A Novel Approach for a Sustainable Environment. Energies 2021, 14, 2937 .

AMA Style

Muhammad Usman, Muhammad Jamil, Fahid Riaz, Haris Hussain, Ghulam Hussain, Muhammad Shah, Muhammad Qyyum, Chaudhary Salman, Moonyong Lee. Refining and Reuse of Waste Lube Oil in SI Engines: A Novel Approach for a Sustainable Environment. Energies. 2021; 14 (10):2937.

Chicago/Turabian Style

Muhammad Usman; Muhammad Jamil; Fahid Riaz; Haris Hussain; Ghulam Hussain; Muhammad Shah; Muhammad Qyyum; Chaudhary Salman; Moonyong Lee. 2021. "Refining and Reuse of Waste Lube Oil in SI Engines: A Novel Approach for a Sustainable Environment." Energies 14, no. 10: 2937.

Journal article
Published: 14 May 2021 in Energies
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This paper describes an ejector model for the prediction of on-design performance under available conditions. This is a direct method of calculating the optimal ejector performance (entrainment ratio or ER) without the need for iterative methods, which have been conventionally used. The values of three ejector efficiencies used to account for losses in the ejector are calculated by using a systematic approach (by employing CFD analysis) rather than the hit and trial method. Both experimental and analytical data from literature are used to validate the presented analytical model with good agreement for on-design performance. R245fa working fluid has been used for low-grade heat applications, and Engineering Equation Solver (EES) has been employed for simulating the proposed model. The presented model is suitable for integration with any thermal system model and its optimization because of its direct, non-iterative methodology. This model is a non-dimensional model and therefore requires no geometrical dimensions to be able to calculate ejector performance. The model has been validated against various experimental results, and the model is employed to generate the ejector performance curves for R245fa working fluid. In addition, system simulation results of the ejector refrigeration system (ERS) and combined cooling and power (CCP) system have been produced by using the proposed analytical model.

ACS Style

Fahid Riaz; Fu Yam; Muhammad Qyyum; Muhammad Shahzad; Muhammad Farooq; Poh Lee; Moonyong Lee. Direct Analytical Modeling for Optimal, On-Design Performance of Ejector for Simulating Heat-Driven Systems. Energies 2021, 14, 2819 .

AMA Style

Fahid Riaz, Fu Yam, Muhammad Qyyum, Muhammad Shahzad, Muhammad Farooq, Poh Lee, Moonyong Lee. Direct Analytical Modeling for Optimal, On-Design Performance of Ejector for Simulating Heat-Driven Systems. Energies. 2021; 14 (10):2819.

Chicago/Turabian Style

Fahid Riaz; Fu Yam; Muhammad Qyyum; Muhammad Shahzad; Muhammad Farooq; Poh Lee; Moonyong Lee. 2021. "Direct Analytical Modeling for Optimal, On-Design Performance of Ejector for Simulating Heat-Driven Systems." Energies 14, no. 10: 2819.

Journal article
Published: 12 May 2021 in Sustainable Energy Technologies and Assessments
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The burning of fossil fuels in power sectors for energy generating purposes and in agricultural country like Pakistan the residues of crops on large area of land are burnt every year that results in continuous addition of CO2 in environment. CO2 capture through solid based adsorbents is one of the best valued, echo friendly and techno-economic processes. The present research involves the development of activated carbons using five different waste biomass materials through single step chemical activation for effective CO2 adsorption, study of isosteric heat of adsorption and change in these values with a change in level of CO2 adsorbed. Chemical activation with single-step method was carried out to prepare the adsorbents. The samples were characterized and compared for the textural properties by recording isotherms of nitrogen adsorption at temperature of 77 K while CO2 adsorption curves at 273 K then at 298 K. SEM was brought into use to investigate morphological characters, surface morphology of activated carbons that confirms the presence of random micro-pores. Nonlinear density functional theory (NDLFT) strengthen the fact that CO2 adsorption depends upon the volume of pores. Samples have pore volume ranging from 0.11 cm3 to 0.44 cm3, whereas BET surface area values were observed from 439 m2/g up to 979 m2/g. Among the prepared activated carbons, the sample with date seeds as base material showed the uppermost uptake of 5.8 mmol/g at 273 K. Linear fitting of the curve between CO2 adsorbed and pore volume at a temperature of 273 K and 298 K with R2 values greater than 0.9 demonstrate the strong relation between pore volume, temperature and CO2 adsorbed. Isosteric heat of adsorption (IHA) values were found to be in the assortment of 44 KJ/mol with minimum value of 14.3 KJ/mol that decreases with increase of CO2 adsorption. High isosteric heat means strong interaction of CO2 molecules and prepared adsorbents. Obtained results confer base to use waste biomass materials for development of solid based adsorbents and use of these adsorbents in effective carbon capture applications to reduce the carbon footprints in the environment and avoid the waste burning of biomass residues.

ACS Style

Hamza Mumtaz; M. Farhan; M. Amjad; Fahid Riaz; Ali H. Kazim; M. Sultan; M. Farooq; M.A. Mujtaba; I. Hussain; M. Imran; Saqib Anwar; Ahmed M. El-Sherbeeny; Farrukh A. Siddique; Stevan Armaković; Qasim Ali; Ijaz A. Chaudhry; Alberto Pettinau. Biomass waste utilization for adsorbent preparation in CO2 capture and sustainable environment applications. Sustainable Energy Technologies and Assessments 2021, 46, 101288 .

AMA Style

Hamza Mumtaz, M. Farhan, M. Amjad, Fahid Riaz, Ali H. Kazim, M. Sultan, M. Farooq, M.A. Mujtaba, I. Hussain, M. Imran, Saqib Anwar, Ahmed M. El-Sherbeeny, Farrukh A. Siddique, Stevan Armaković, Qasim Ali, Ijaz A. Chaudhry, Alberto Pettinau. Biomass waste utilization for adsorbent preparation in CO2 capture and sustainable environment applications. Sustainable Energy Technologies and Assessments. 2021; 46 ():101288.

Chicago/Turabian Style

Hamza Mumtaz; M. Farhan; M. Amjad; Fahid Riaz; Ali H. Kazim; M. Sultan; M. Farooq; M.A. Mujtaba; I. Hussain; M. Imran; Saqib Anwar; Ahmed M. El-Sherbeeny; Farrukh A. Siddique; Stevan Armaković; Qasim Ali; Ijaz A. Chaudhry; Alberto Pettinau. 2021. "Biomass waste utilization for adsorbent preparation in CO2 capture and sustainable environment applications." Sustainable Energy Technologies and Assessments 46, no. : 101288.

Journal article
Published: 24 April 2021 in Energies
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Heat storage with thermochemical (TC) materials is a promising technology for solar energy storage. In this paper, a solar-driven desiccant evaporative cooling (DEC) system for air-conditioning is proposed, which converts solar heat energy into cooling with built-in daily storage. The system utilises thermochemical heat storage along with the DEC technology in a unique way. Magnesium Chloride (MgCl2·6H2O) has been used, which serves as both a desiccant and a thermochemical heat storage medium. The system has been designed for the subtropical climate of Lahore, Pakistan, for a bedroom with 8 h of cooling requirements during the night. MATLAB has been employed for modelling the system. The simulation results show that 57 kg of magnesium chloride is sufficient to meet 98.8% of cooling demand for the entire month of July at an elevated cooling requirement. It was found that the cooling output of the system increased with increasing heat exchanger effectiveness. The heat exchangers’ effectiveness was increased from 0.7 to 0.8, with the solar fraction increased from 70.4% to 82.44%. The cooled air supplied to the building meets the fresh air requirements for proper ventilation.

ACS Style

Fahid Riaz; Muhammad Qyyum; Awais Bokhari; Jiří Klemeš; Muhammad Usman; Muhammad Asim; Muhammad Awan; Muhammad Imran; Moonyong Lee. Design and Energy Analysis of a Solar Desiccant Evaporative Cooling System with Built-In Daily Energy Storage. Energies 2021, 14, 2429 .

AMA Style

Fahid Riaz, Muhammad Qyyum, Awais Bokhari, Jiří Klemeš, Muhammad Usman, Muhammad Asim, Muhammad Awan, Muhammad Imran, Moonyong Lee. Design and Energy Analysis of a Solar Desiccant Evaporative Cooling System with Built-In Daily Energy Storage. Energies. 2021; 14 (9):2429.

Chicago/Turabian Style

Fahid Riaz; Muhammad Qyyum; Awais Bokhari; Jiří Klemeš; Muhammad Usman; Muhammad Asim; Muhammad Awan; Muhammad Imran; Moonyong Lee. 2021. "Design and Energy Analysis of a Solar Desiccant Evaporative Cooling System with Built-In Daily Energy Storage." Energies 14, no. 9: 2429.

Journal article
Published: 24 February 2021 in Energies
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Constructing the power curve of a power generation facility integrated with complex and large-scale industrial processes is a difficult task but can be accomplished using Industry 4.0 data analytics tools. This research attempts to construct the data-driven power curve of the generator installed at a 660 MW power plant by incorporating artificial intelligence (AI)-based modeling tools. The power produced from the generator is modeled by an artificial neural network (ANN)—a reliable data analytical technique of deep learning. Similarly, the R2.ai application, which belongs to the automated machine learning (AutoML) platform, is employed to show the alternative modeling methods in using the AI approach. Comparatively, the ANN performed well in the external validation test and was deployed to construct the generator’s power curve. Monte Carlo experiments comprising the power plant’s thermo-electric operating parameters and the Gaussian noise are simulated with the ANN, and thus the power curve of the generator is constructed with a 95% confidence interval. The performance curves of industrial systems and machinery based on their operational data can be constructed using ANNs, and the decisions driven by these performance curves could contribute to the Industry 4.0 vision of effective operation management.

ACS Style

Waqar Ashraf; Ghulam Uddin; Muhammad Farooq; Fahid Riaz; Hassan Ahmad; Ahmad Kamal; Saqib Anwar; Ahmed El-Sherbeeny; Muhammad Khan; Noman Hafeez; Arman Ali; Abdul Samee; Muhammad Naeem; Ahsaan Jamil; Hafiz Hassan; Muhammad Muneeb; Ijaz Chaudhary; Marcin Sosnowski; Jaroslaw Krzywanski. Construction of Operational Data-Driven Power Curve of a Generator by Industry 4.0 Data Analytics. Energies 2021, 14, 1227 .

AMA Style

Waqar Ashraf, Ghulam Uddin, Muhammad Farooq, Fahid Riaz, Hassan Ahmad, Ahmad Kamal, Saqib Anwar, Ahmed El-Sherbeeny, Muhammad Khan, Noman Hafeez, Arman Ali, Abdul Samee, Muhammad Naeem, Ahsaan Jamil, Hafiz Hassan, Muhammad Muneeb, Ijaz Chaudhary, Marcin Sosnowski, Jaroslaw Krzywanski. Construction of Operational Data-Driven Power Curve of a Generator by Industry 4.0 Data Analytics. Energies. 2021; 14 (5):1227.

Chicago/Turabian Style

Waqar Ashraf; Ghulam Uddin; Muhammad Farooq; Fahid Riaz; Hassan Ahmad; Ahmad Kamal; Saqib Anwar; Ahmed El-Sherbeeny; Muhammad Khan; Noman Hafeez; Arman Ali; Abdul Samee; Muhammad Naeem; Ahsaan Jamil; Hafiz Hassan; Muhammad Muneeb; Ijaz Chaudhary; Marcin Sosnowski; Jaroslaw Krzywanski. 2021. "Construction of Operational Data-Driven Power Curve of a Generator by Industry 4.0 Data Analytics." Energies 14, no. 5: 1227.

Journal article
Published: 01 January 2021 in Thermal Science
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A number of thermal management devices are used to actuate concentrated electronic appliances in an efficient way. A liquid cooling plate acts as a heat sink enclosed by materialized walls. This work aims to carry out design of liquid cooling plates such that the heat diffused by the electronic equipment is removed while their temperatures levels remain within safe limits. The liquid cooling plates expose ?cold surfaces? to electronic appliances. The performance of a cooling plate is estimated depending upon heat carrying capacity, associated heat transfer rates and concentrated thermal regions on the plate surface. For this study, the design of liquid cooling plate was done with SOLIDWORKS. Pure water was used as a working fluid in test channels. A comparative analysis of flow distribution, temperature contours, pressure drop and pumping power for different channel configurations was carried out with ANSYS. It was observed that a channel configuration is of key importance in liquid cooling plates. The findings from this study are beneficial for the optimum design of cooling systems for high heat flux applications, i.e., in electronic devices, computer processors and automotive engines.

ACS Style

Muhammad Farhan; Muhammad Amjad; Zia Ul Rehman Tahir; Zahid Anwar; Muhammad Arslan; Ahmad Mujtaba; Fahid Riaz; Shahid Imran; Luqman Razzaq; Mudassar Ali; Enio P. Bandarra Filho; Du. Xioze. Design and analysis of liquid cooling plates for different flow channel configurations. Thermal Science 2021, 196 -196.

AMA Style

Muhammad Farhan, Muhammad Amjad, Zia Ul Rehman Tahir, Zahid Anwar, Muhammad Arslan, Ahmad Mujtaba, Fahid Riaz, Shahid Imran, Luqman Razzaq, Mudassar Ali, Enio P. Bandarra Filho, Du. Xioze. Design and analysis of liquid cooling plates for different flow channel configurations. Thermal Science. 2021; (00):196-196.

Chicago/Turabian Style

Muhammad Farhan; Muhammad Amjad; Zia Ul Rehman Tahir; Zahid Anwar; Muhammad Arslan; Ahmad Mujtaba; Fahid Riaz; Shahid Imran; Luqman Razzaq; Mudassar Ali; Enio P. Bandarra Filho; Du. Xioze. 2021. "Design and analysis of liquid cooling plates for different flow channel configurations." Thermal Science , no. 00: 196-196.

Journal article
Published: 04 October 2020 in Sustainability
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Low-grade heat is abundantly available as solar thermal energy and as industrial waste heat. Non concentrating solar collectors can provide heat with temperatures 75–100 °C. In this paper, a new system is proposed and analyzed which enhances the electrical coefficient of performance (COP) of vapour compression cycle (VCC) by incorporating low-temperature heat-driven ejectors. This novel system, ejector enhanced vapour compression refrigeration cycle (EEVCRC), significantly increases the electrical COP of the system while utilizing abundantly available low-temperature solar or waste heat (below 100 °C). This system uses two ejectors in an innovative way such that the higher-pressure ejector is used at the downstream of the electrically driven compressor to help reduce the delivery pressure for the electrical compressor. The lower pressure ejector is used to reduce the quality of wet vapour at the entrance of the evaporator. This system has been modelled in Engineering Equation Solver (EES) and its performance is theoretically compared with conventional VCC, enhanced ejector refrigeration system (EERS), and ejection-compression system (ECS). The proposed EEVCRC gives better electrical COP as compared to all the three systems. The parametric study has been conducted and it is found that the COP of the proposed system increases exponentially at lower condensation temperature and higher evaporator temperature. At 50 °C condenser temperature, the electrical COP of EEVCRC is 50% higher than conventional VCC while at 35 °C, the electrical COP of EEVCRC is 90% higher than conventional VCC. For the higher temperature heat source, and hence the higher generator temperatures, the electrical COP of EEVCRC increases linearly while there is no increase in the electrical COP for ECS. The better global COP indicates that a small solar collector will be needed if this system is driven by solar thermal energy. It is found that by using the second ejector at the upstream of the electrical compressor, the electrical COP is increased by 49.2% as compared to a single ejector system.

ACS Style

Fahid Riaz; Kah Hoe Tan; Muhammad Farooq; Muhammad Imran; Poh Seng Lee. Energy Analysis of a Novel Ejector-Compressor Cooling Cycle Driven by Electricity and Heat (Waste Heat or Solar Energy). Sustainability 2020, 12, 8178 .

AMA Style

Fahid Riaz, Kah Hoe Tan, Muhammad Farooq, Muhammad Imran, Poh Seng Lee. Energy Analysis of a Novel Ejector-Compressor Cooling Cycle Driven by Electricity and Heat (Waste Heat or Solar Energy). Sustainability. 2020; 12 (19):8178.

Chicago/Turabian Style

Fahid Riaz; Kah Hoe Tan; Muhammad Farooq; Muhammad Imran; Poh Seng Lee. 2020. "Energy Analysis of a Novel Ejector-Compressor Cooling Cycle Driven by Electricity and Heat (Waste Heat or Solar Energy)." Sustainability 12, no. 19: 8178.

Conference paper
Published: 17 June 2020 in ASME 2020 14th International Conference on Energy Sustainability
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In this paper, a new combined cooling and power (CCP) system has been proposed which enables harnessing of very low-grade heat (< 100 °C) in an effective way. The novel system configuration uses two vapour generators to extract more heat from heating stream and employs ejector in a unique way to serve two purposes; (i) to reduce pressure at the expander outlet for more power output (ii) vapour compression for refrigeration. The system is modelled in EBSILON which is a commercial thermal design and optimization tool. For ejector performance prediction, a new on-design optimal performance analytical model is used which is developed in EES (Engineering Equation Solver). The parametric study shows that when the evaporator pressure is changed from 0.8 bar (9.4 °C) to 1.2 bar (19.5 °C) the output of the system is increased by 58 % and when the condenser pressure is changed from 1.8 bar (30.5 °C) to 2.2 bar (36.2 °C) the system output is dropped by 56.4 %.

ACS Style

Fahid Riaz; Muhammad Farooq; Muhammad Imran; Poh Seng Lee; Siaw Kiang Chou. Energy Analysis of a New Combined Cooling and Power System for Low-Temperature Heat Utilization. ASME 2020 14th International Conference on Energy Sustainability 2020, 1 .

AMA Style

Fahid Riaz, Muhammad Farooq, Muhammad Imran, Poh Seng Lee, Siaw Kiang Chou. Energy Analysis of a New Combined Cooling and Power System for Low-Temperature Heat Utilization. ASME 2020 14th International Conference on Energy Sustainability. 2020; ():1.

Chicago/Turabian Style

Fahid Riaz; Muhammad Farooq; Muhammad Imran; Poh Seng Lee; Siaw Kiang Chou. 2020. "Energy Analysis of a New Combined Cooling and Power System for Low-Temperature Heat Utilization." ASME 2020 14th International Conference on Energy Sustainability , no. : 1.

Journal article
Published: 28 November 2019 in Applied Thermal Engineering
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This paper presents the modeling and optimization of an ejector refrigeration system (ERS). Engineering Equation Solver (EES) has been used for modeling. These models have been validated against published experimental results. Refrigerant R245fa is used as a working fluid. A new analytical model for predicting the optimum (on-design) performance (entrainment ratio) of ejectors is presented. The analytical model of the ejector is validated against two sets of published experimental data and good agreement is established with an average error of 3.4%. The presented ERS model has also been validated with two sets of published experimental results and an average error of 2.9% is obtained. The ERS model is further compared with a model developed in EBSILON (a commercial tool). The results show that for the optimum design of an ERS, the generator pressure increases linearly with heat source temperature while the output (refrigeration effect) increases exponentially. For the case study, the designed ERS produces 1.8 MW of cooling with estimated annual savings of S$0.42 million while operating at 0.3 COP. The presented models can be used for designing ejector and ERS for various applications.

ACS Style

Fahid Riaz; Ps Lee; Siaw Kiang Chou. Thermal modelling and optimization of low-grade waste heat driven ejector refrigeration system incorporating a direct ejector model. Applied Thermal Engineering 2019, 167, 114710 .

AMA Style

Fahid Riaz, Ps Lee, Siaw Kiang Chou. Thermal modelling and optimization of low-grade waste heat driven ejector refrigeration system incorporating a direct ejector model. Applied Thermal Engineering. 2019; 167 ():114710.

Chicago/Turabian Style

Fahid Riaz; Ps Lee; Siaw Kiang Chou. 2019. "Thermal modelling and optimization of low-grade waste heat driven ejector refrigeration system incorporating a direct ejector model." Applied Thermal Engineering 167, no. : 114710.

Journal article
Published: 01 June 2018 in Applied Energy
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Micro spacecraft, which have gained huge popularity in the last decade, are termed as “CubeSats”, a well-known class of small satellites. The fast growing functionality and popularity of CubeSats have helped researchers push technology demonstration towards efficient performance and reliability needed for commercial and governmental applications. Keeping in mind the increasing space debris, dependence of satellite life on fuel, and the use of fossil fuels as propellants, recent efforts are being made to develop a cold gas propellant-based (CGP) micro propulsion system. The CGP system has various merits, namely, non-toxicity, easy to use, and low leakage concerns over other propulsion systems. Liquid propellant-based propulsion requires a liquid feed system, which uses pressurized gas (such as helium, argon and nitrogen) to pressure-feed liquid to the combustion or vaporization chamber so as to produce thrust. But once the liquid propellant is depleted, the pressurized gas is unusable while the system runs out of fuel. Thus, the proposed CGP system being studied, apart from being used as a normal cold gas propulsion system, also offers the advantage of being used as a propulsion system for a liquid fueled system, in the event the liquid fuel runs out. The present work reports on cold gas micro thruster development, utilization of feed gas in a liquid fueled thruster, and the experimental study on the CGP system in simulated vacuum conditions and under a range of pressure conditions. Pressure in the pressure feed gas system for a 1–50 kg category of satellites varies from 4 to 8 bar depending on the mission requirement. The pressure reduces as the liquid propellant gets exhausted. The experimental results are used to validate a computational fluid dynamics model of the system. Thrust values are obtained between the micro to milli-Newton range so as to fulfil the requirements of attitude and station keeping for CubeSats in the 1–50 kg dry mass range. Under vacuum conditions, we obtained thrust values of 0.8 mN at 1 bar feed pressure to 2.24 mN at 4 bar feed pressure. These thrust values are nearly twice those achieved for sea level tests for the corresponding feed pressure. Furthermore, the parameters such as Mach number, velocity vector, pressure, temperature, specific impulse, and nozzle efficiency are studied and reported for atmospheric and vacuum conditions.

ACS Style

R. Ranjan; K. Karthikeyan; F. Riaz; S.K. Chou. Cold gas propulsion microthruster for feed gas utilization in micro satellites. Applied Energy 2018, 220, 921 -933.

AMA Style

R. Ranjan, K. Karthikeyan, F. Riaz, S.K. Chou. Cold gas propulsion microthruster for feed gas utilization in micro satellites. Applied Energy. 2018; 220 ():921-933.

Chicago/Turabian Style

R. Ranjan; K. Karthikeyan; F. Riaz; S.K. Chou. 2018. "Cold gas propulsion microthruster for feed gas utilization in micro satellites." Applied Energy 220, no. : 921-933.

Journal article
Published: 01 December 2017 in Energy Procedia
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ACS Style

Fahid Riaz; Poh Seng Lee; Siaw Kiang Chou; Ravi Ranjan; Cher Seng Tay; Thazin Soe. Analysis of Low-Grade Waste Heat Driven Systems for Cooling and Power for Tropical Climate. Energy Procedia 2017, 143, 389 -395.

AMA Style

Fahid Riaz, Poh Seng Lee, Siaw Kiang Chou, Ravi Ranjan, Cher Seng Tay, Thazin Soe. Analysis of Low-Grade Waste Heat Driven Systems for Cooling and Power for Tropical Climate. Energy Procedia. 2017; 143 ():389-395.

Chicago/Turabian Style

Fahid Riaz; Poh Seng Lee; Siaw Kiang Chou; Ravi Ranjan; Cher Seng Tay; Thazin Soe. 2017. "Analysis of Low-Grade Waste Heat Driven Systems for Cooling and Power for Tropical Climate." Energy Procedia 143, no. : 389-395.

Journal article
Published: 30 April 2015 in International Journal of Sustainable Energy
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ACS Style

Muhammad Rizwan Awan; Fahid Riaz; Zahid Nabi. Analysis of conditions favourable for small vertical axis wind turbines between building passages in urban areas of Sweden. International Journal of Sustainable Energy 2015, 36, 1 -12.

AMA Style

Muhammad Rizwan Awan, Fahid Riaz, Zahid Nabi. Analysis of conditions favourable for small vertical axis wind turbines between building passages in urban areas of Sweden. International Journal of Sustainable Energy. 2015; 36 (5):1-12.

Chicago/Turabian Style

Muhammad Rizwan Awan; Fahid Riaz; Zahid Nabi. 2015. "Analysis of conditions favourable for small vertical axis wind turbines between building passages in urban areas of Sweden." International Journal of Sustainable Energy 36, no. 5: 1-12.