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WHB ( Waste Heat Boiler ) merupakan bejana tertutup yang memanfaatkan panas atau gas buang untuk pembakarannya, panas pembakaran tersebut dialirkan ke air sampai terbentuk air panas atau steam yang akan digunakan untuk memutar sudu-sudu pada turbin. WHB Unit IIIA PT. Petrokimia Gresik mempunyai umur yang sudah cukup lama yaitu mulai beroperasi tahun 1974. Umur WHB yang sudah cukup tua ini menyebabkan kinerja menurun. WHB Unit IIIA PT Petrokimia Gresik memanfaatkan gas buang dari furnace proses pembakaran belerang cair menjadi gas SO 2 , namun kinerja dari WHB belum maksimum. Penelitian ini menggunakan metode perhitungan heat exchanger Kern 1983. Berdasarkan hasil evaluasi terhadap nilai coefficient clean overall aktual rata-rata 520,90 W/m 2 , coefficient dirt overall aktual rata-rata 40,52 W/m 2 , dan fouling factor aktual rata-rata 0,0241 m 2 .K/W, dapat disimpulkan bahwa WHB masih layak beroperasi. Namun, jika digunakan terus-menerus tanpa dilakukan pembersihan akan mengurangi kinerja WHB. Oleh karena itu, perlu dilakukan pembersihan secara berkala untuk menjaga kinerja WHB agar tetap beroperasi dengan baik.

In the present work, the performance improvement of a waste heat recovery system is investigated by applying a fuel cell and thermoelectric generator. With the use of energy, exergy, exergo-economic, and environmental analyses (4E analysis), the performance of the improved system is evaluated. A mathematical simulation in the Engineering Equation Solver (EES) is developed for basic and modified systems. Comparative analysis is carried out to demonstrate the benefit of the suggested system. The logical and correct combination of appropriate subsystems can lead to the maximum exploitation of an energy source, which is the innovation of the present work. The comparison of suggested system (PR/FC-TEG) with the CHP system indicates that the net output power of the PR/FC-TEG system is 3881 kW compared with 958.4 kW for the CHP system. However adding fuel cell to the PR/FC-TEG system increase output power by about 2162 kW, and it imposes 4823 kW exergy destruction rate to the system. The exergy destruction rate of the PEM FC, regenerator, and vapor generator are about 88.96% of the total exergy destruction rate, which infers the importance of these components in the PR/FC-TEG system improvement. Parametric analysis on the PR/FC-TEG performance with changing four influencing parameters is performed. Results indicate that increasing the turbine 1 inlet temperature by about 1.1% increases the cost of generated electricity from 72.92 to 73.88 $/GJ and decreases the sustainability index from 1.68 to 1.65. The multi-objective optimization of the developed system can be a promising option for future study.

In the current study, biomass was employed as the primary fuel in a multigenerational system to produce power, heat, and hydrogen. Biomass gasification unit, dual fuel homogeneous charge compression ignition (HCCI) engine, Rankine cycle, and waste heat recovery units are the main components of the developed system. The engine exhaust gas contains waste heat which can be utilized for biomass gasification. Hydrogen is the main output of the system whose specific fraction is introduced to the Heptane fueled HCCI engine. The results of the gasification unit and HCCI engine are in good agreement with the experimental reports in the literature. The cold gas and hydrogen efficiencies of the biomass gasification unit were 73% and 34%, respectively. Furthermore, the use of hydrogen as an additional fuel to the heptane-fueled HCCI engine improved the performance of the engine. Except for N O x , other emissions showed a decline. Results indicated that energy efficiency exceeded 57%, while the energy efficiency of the HCCI engine is 38%. Moreover, the exergy efficiency increased from 29% in the single HCCI engine to 47% in the proposed system.

Thermal energy storage (TES) is playing a vital role in various applications and this paper intends to provide an overview of different applications involved in various areas. This work mainly focuses on review of TES applications in wide area such as waste heat recovery, Heavy electronic equipment’s cooling etc. The comprehensive study shows that thermal energy stored can be used for heating and cooling applications and have a great scope for developing new technology and methods for utilizing it to maximum extent. Exploring various thermal storage materials and methods for different application opening many ways towards the sustainable development and utilization of available thermal energy.

Contamination and waste heat are major issues in water pollution. Aiming at efficient synchronous recovery wastewater and waste heat, we designed a novel CaCO3-based phase-change microcapsule system with an n-docosane core and a CaCO3/Fe3O4 composite shell. The system was fabricated through an emulsion-templated in situ precipitation approach in a structure-directing mode, resulting in a controllable morphology for the resultant microcapsules, varying from a peanut hull through ellipsoid to dumbbell shapes. The system has a significantly enlarged specific surface area of approximately 55 m2·g−1 with the CaCO3 phase transition from vaterite to calcite. As a result, the microcapsule system exhibits improved adsorption capacities of 497.6 and 79.1 mg/g for Pb2+ and Rhodamine B removal, respectively, from wastewater. Moreover, increase in the specific surface area of the microcapsule system with a sufficient latent heat capacity of approximately 130 J·g−1 also resulted in an enhanced heat energy-storage capability and thermal conductance for waste-heat recovery. The microcapsule system also exhibits a good leakage-prevention capability and good multicycle reusability owing to the tight magnetic CaCO3/Fe3O4 composite shell. This study provides a promising approach for developing CaCO3-based phase-change microcapsules with enhanced thermal energy storage and adsorption capabilities for efficient synchronous recovery of wastewater and waste heat.

Due to the rapid exploitation of fossil fuels, energy sources are becoming nonrenewable, and there is a need to develop other technologies to provide a clean supply of energy. The heat is stored in the thermal storage unit utilizing phase change materials in one of two ways: sensible heat or latent heat. When the temperature of phase change materials rises, energy stored in the perceptible form in the materials rises as well. While latent heat is stored during phase change of materials during the charging process and retrieved during phase change discharging at a virtually constant temperature during the discharging process. Latent heat has a large capacity to store a large amount of thermal energy per unit space. The use of phase change material (PCM) can be found in a variety of fields, including: • Improving the efficiency of photovoltaic cell. • Thermal storage of solar energy. • Waste heat recovery. • Engine cooling. • Building cooling to store energy during peak time and retrieving during requirement. The main drawback of PCM is its low thermal conductivity, which can be increased by incorporating fins and adding nanoparticles (to enhance heat transfer) in PCM. Our task in this study was to evaluate literature and develop applications for PCM, as well as to reduce PCM charging and discharging by boosting the rate of heat transfer.

This work presents an energy, exergy, and environmental evaluation of a novel compound PV/T (photovoltaic thermal) waste heat driven ejector-heat pump system for simultaneous data center cooling and waste heat recovery for district heating networks. The system uses PV/T waste heat with an evaporative-condenser as a driving force for an ejector while exploiting the generated electric power to operate the heat pump compressor and pumps. The vapor compression system assessed several environmentally friendly strategies. The study compares eleven lower global warming potential (GWP) refrigerants from different ASHRAE safety groups (R450A, R513A, R515A, R515B, R516A, R152a, R444A, R1234ze(E), R1234yf, R290, and R1243zf) with the hydrofluorocarbon (HFC) R134a. The results prove that the system presents a remarkable overall performance enhancement for all investigated refrigerants in both modes. Regarding the energy analysis, the cooling coefficient of performance (COPC) enhancement ranges from 15% to 54% compared with a traditional R134a heat pump. The most pronounced COPC enhancement is caused by R515B (a 54% COPC enhancement and 49% heating COP enhancement), followed by R515A and R1234ze(E). Concerning the exergy analysis, R515B shows the lowest exergy destruction, with the highest exergy efficiency than all investigated refrigerants. Funding for open access charge: CRUE-Universitat Jaume I

In some thermally driven two-phase natural circulation systems, bubble pumps serve as the key driving powers for the cycles. Recently a type of distribute heating bubble pump generator (BPG) is gradually receiving attention due to its compact structure and great potentials to utilize solar energy and low-grade waste heat recovery. The BPG provides a variety of promising features (e.g., passive heat transfer, enhanced reliability), which can benefit the advancing of heat transfer technology. For the primary study, we performed an experiment in a distributed heating BPG. Through utilizing multiple lift tubes and partial visualization configurations, it provides accesses to observe the flow pattern transition and monitor the flow instability, and thus to explore some of the underlying mechanisms affecting BPG performance. Results showed that heat input and immersion height were crucial parameters to enable the operation of distribute heating BPG. With low heat input or high inlet water subcooling level, the flow within the pump was unstable with intermittent flow interruptions. As the heat input increased, the fluid flow became more stable, the vapor generation increased linearly, while the lifted liquid flow rate initially increased then decreased. Correspondingly, the flow pattern at the outlet section of lift tubes gradually changed from slug flow to churn flow, and then to annular flow. The higher of the immersion was, the higher heat input was needed for the flow pattern transition. It was in the churn flow regime at the outlet of lift tubes for the BPG to lift a maximum liquid. At lower immersion level, liquid reflux in the lift tubes was obvious and affected the flow stability as well as the lifting performance. At higher immersion level, the fluid flow was more stable and faster, which lifted more liquid while generated less vapor depending on the inlet subcooling. In general, the BPG showed better performance (both the lifted liquid and vapor generation increased) at smaller inlet subcooling level or lower system pressure. This study highlights the flow pattern evolution and flow stability, which is helpful to the reliable design and effective operation of the distributed heating BPG.

Chemical energy is not effectively converted into mechanical energy by an internal combustion engine. Major portion of heat energy get dissipated with exhaust and coolant. Use of thermoelectric generator (TEG) technology is regarded as an environment friendly technique for recovering the waste heat, with which heat energy directly converts into electrical energy. In this study, an experiment is conducted in which TEG technology has been used to recover waste heat going out through exhaust gas from the diesel engine. Thermoelectric modules were fixed on the surface of stainless steel made pipe having square cross-section. It has been found that the power output of thermoelectric generator enhances with the increase in engine load. The maximum electrical power output of TEG has been obtained as 37 W at maximum load of 6 kg. Overall thermal efficiency of diesel engine has also been improved with the use of TEG type of waste heat recovery system.

Depending on their applications, heat losses from the shells of rotary kilns account for 3 to 25% of the total heat input. Over the hottest zone of the kiln shell, an annular duct with a variable diameter is formed. Two air streams entering the annulus at both ends flow to a common extraction point to receive the thermal power equal to the ambient heat loss of the bare kiln. The design does not require airtightness, utilizes the entire heat loss, and by the variation of the airflow can be used over the kilns with variable operating parameters (±20% heat loss), which show similar surface temperature patterns. The main disadvantage of the design is the approaching of the surfaces of the kiln and the recuperator at the outlet of preheated air. This means that for a given heat loss and a surface temperature pattern, the rotational eccentricity of the kiln shell is the most influencing parameter that defines the air preheating temperature and the efficiency of the recuperator. To solve the problem, 4 redesigns with: (i) double annuluses, (ii) the usage of radiation fins, (iii) air addition, and (iv) a combination of two basic designs are analyzed by the use of analytical and CFD models. From the listed redesigns: (i) could be used only to prevent overheating, (ii) has a modest positive effect, (iii) should be applied in combination with (iv).

Several studies have novel distributed energy systems combining solar energy utilization and hybrid energy storage technology. However, the research on thermodynamic performance and optimization design of the novel system is still insufficient. Therefore, a novel distributed energy system uses a jacket water heat exchanger and a waste heat boiler to recover the waste heat of the internal combustion engine in turn and shares a water tank with the solar thermal collector in parallel. Then, the influence of different parameters on the thermodynamic performance of the system under variable working conditions is analyzed by the parametric analysis method. On this basis, an optimization design method considering the thermodynamic and economic performance of the novel system is proposed. The novel system is applied to a nearly zero-energy community with an electric vehicle charge load. The results show that the exergy efficiency, primary energy rate, and cost per unit supply area of the novel system in a typical year are 19.2%, 70.1%, and 5.4 $/m2, respectively. Therefore, the novel system is reliable and feasible in providing all kinds of energy to users.

A novel dual source vapor injection heat pump (DSVIHP) using exhaust and ambient air is proposed. The air exhausted from the building first releases energy to the medium-pressure evaporator and is then mixed with the ambient air to heat the low-pressure evaporator. A vapor injection (VI) compressor of two inlets is connected with the low and medium pressure evaporators. It's first time that a VI compressor is employed to recover the ventilation heat. The system can minimize the ventilation heat loss and provide a unique defrosting approach by using the exhaust waste heat. Fundamentals of the proposed DSVIHP are illustrated. Mathematical models are built. Both energetic and exergetic analyses are carried out under variable conditions. The results indicate that the DSVIHP has superior thermodynamic performance. The superiority is more appreciable at a lower ambient temperature. It has a higher COP than the conventional vapor injection heat pump and air source heat pump by 11.3% and 23.2% respectively at an ambient temperature of -10 °C and condensation temperature of 45 °C. The waste heat recovery ratio from the exhaust air is more than 100%. The novel DSVIHP has great potential in the cold climate area application.

This article reports on using Kalina cycle for waste heat recovery from a cement plant. Two design alternatives have been investigated using separate and combined waste heat recovery from the kiln, cooler, and preheater. Measurements and analysis have been performed to determine the waste heat from different stages of the cement manufacturing lines. The annual heat losses from the kiln surface, preheater, and the cooler are estimated as 79.23 GWh, 44.32 GWh, and 43.6 GWh at average temperatures of about 314?, 315?, and 254?, respectively. Analysis and optimization of using Kalina cycle for waste heat recovery from the kiln shell, cooler and preheater to produce electricity have been carried out using ASPEN software. Parametric study has been carried out to determine the design parameters for Kalina cycle including turbine inlet pressure, mass-flow rate, and NH3-H2O concentration. The value of net power output using combined waste heat recovery is about 7.35 MW as compared to 6.86 using separate waste heat recovery design with a total cost saving of about 23%.

This paper develops a four-step copper-chlorine cycle for hydrogen production with conceptual modification through flash vaporization and evaluates its economic and environmental performances through exergy approach. The flash vaporization method is employed as a new approach for realizing the anolyte separation under vacuum conditions for reducing the thermal requirement of the anolyte separation step and consequently of the overall cycle. A flash vaporization is usually employed commercially for seawater desalination purposes. However, its utilization in a thermochemical hydrogen production process has not been considered previously which is really one of primary novelties of this investigation. The obtained results for the exergoeconomic and exergoenvironmental analyses of the conceptually modified cycle are also compared with those of the existing integrated cycle at the Ontario Tech University. The exergoeconomic analysis of the cycle has also been carried out for the cycle operating with and without waste heat recovery. In this regard, waste heat recovery from a steel furnace has been considered for supplying the required thermal energy for the hydrolysis step. The cost assessment of the cycle is carried out in the Aspen-plus. Compared with the existing cycle, the cycle with the proposed modification results in a lower unit cost of hydrogen. Moreover, a significant reduction in the unit cost of hydrogen is observed when waste heat recovery is considered for the modified cycle. The average unit hydrogen cost for the modified version of the cycle is evaluated to be 4.7 $/kg which reduces to 2 $/kg with incorporation of waste heat recovery. Furthermore, the overall environmental impact of the existing cycle can be potentially minimized by considering the proposed modification through flash vaporization.

This chapter describes a system which recovers waste heat to be used for baking, improving the fuel efficiency of the oven by at least 15%. The heat recovery system uses heat from the burner flues. This may be used to heat one or two final zones of the oven. These zones would not require burners, giving a saving in capital and running costs.

In the current industrial production process, waste heat of low quality is seriously wasted. In order to effectively recover low-quality waste heat, the research group developed a small energy conversion device –Roots power machine. On this basis, the research group designed a low-quality waste heat efficient utilization system with the equipment as the core and successfully applied it to low-quality waste heat recovery. However, in the actual operation process, the system can not run stably due to the occasional fluctuation of the input gas source. In view of this, after the study of waste heat recovery system, the fluctuation of gas source can be controlled by different grades according to the degree of change. Fuzzy rules also divide variables into different grades to solve problems, and fuzzy control can convert continuous changes of airflow into discrete changes, which greatly reduces the complexity of the control system. Therefore, the research group proposed a control strategy based on fuzzy PID. The simulation results show that the adjustment time of fuzzy PID is within 7 s, and the adjustment effect is obviously better than that of traditional PID. The experimental results show that the speed deviation under the condition of air source fluctuation is within the speed fluctuation rate (±5%), and the speed deviation under the condition of sudden disturbance load is within the steady speed adjustment rate (±3.5%), both of which meet the requirements of indexes. Therefore, the fuzzy PID control strategy can further improve the stability of output speed, reduce airflow pulsation, and provide the possibility for grid-connected power generation.

Industrial boilers by using biomass for electricity generation have received significant attention recent years. However, during the process, a significant fraction of thermal energy is often lost to the environment as flue gas. The exhaust flue gas heat loss which ranges from 150-180°C (423.15-453.15K) has led to discovery of importance of recovering the waste heat of the flue gas to overcome the reliance on fossil fuel. Stirling engine as an external combustion engine with high efficiencies and able to use any types of heat source is the best candidate to recover waste heat of the exhausted gas by converting it into power. Thus, in this study Stirling engine was introduced in order to evaluate the possibility of recovering waste heat from industrial boilers to produce power. For this reason, Computational Fluid Dynamic (CFD) simulation test was performed to design an initial computational model of Stirling engine for low temperature heat waste recovery. The CFD model was validated with the experiment model and shows 4.3% of deviation. The validated model then connected to a lower temperature. It shows that when the heat source is 400K, the work done by the engine is 8.4J compared to when heat source 773K the work done is 17.0 J. The computational model can be used to evaluate the performance of Stirling engine as waste heat recovery of biomass-based industrial boilers for low-grade temperature heat source.

This work proposes a novel fluid-thermal-electric multiphysics numerical model to predict the performance of thermoelectric generator systems applied to fluid waste heat recovery, with the consideration of multiphysics coupling effects of fluid, thermal, and electric fields. The comprehensive numerical simulations of the thermoelectric generator system are performed via COMSOL coupled solver. Besides, the effect of the neglect of parasitic heat on the output performance is investigated through the comparison with numerical results predicted by ANSYS and COMSOL separate solver, wherein the fluid-thermal field is computed first, then the thermal-electric field. The results show that the output power predicted by COMSOL separate solver is 8.52% lower than that predicted by COMSOL coupled solver at the inlet air temperature of 550 K and inlet air velocity of 30 m/s due to the neglect of parasitic heat. The output performance of the TEG system predicted by ANSYS is less affected by inlet air boundary conditions than that predicted by COMSOL. Finally, the experimental results show that the fluid-thermal-electric multiphysics model solved by the COMSOL coupled solver shows the lowest output power deviation of 2.81%. The proposed model can guide the numerical modeling of the thermoelectric generator system applied to fluid waste heat recovery.

In the present work a comparative exergy analysis, multi-objective optimization, as well as extended environmental analysis of a geothermal-based power and refrigeration system, is carried out. Different arrangements with the ammonia-water refrigeration cycle, organic Rankine cycle (ORC), and thermoelectric generator (TEG) are investigated. The current work novelties are the presentation of a novel power-refrigeration system driven by a geothermal source and the employment of TEG units to recover geothermal energy, besides extended environmental assessment. The results of sensitivity analysis indicate that the highest net output work capacity is for the suggested system (configuration 3). Exergy analysis exhibits that in all cases, the absorber has the highest exergy destruction rate and one of the lowest exergy efficiency because it is the first component, which gains the heat from the geothermal source. The suggested system produces 495.2 kW net output power and the highest energy efficiency of 19.42%, which are 131.7 kW, and 3.84% higher than configuration 1(base system). Optimization results represent that in the optimum point, W net shows about 33.3% improvement compared with the un-optimized condition. It is found that configuration 3 which consists of cogeneration with two loops of ammonia-water power cycle with refrigeration system along with an additional thermoelectric generator for enhanced waste heat recovery has the highest environmental footprints because of multiple components installed that would occupy more space, electricity, materials, and other resources for its construction, operation, maintenance, and end-of-life.

To enhance the performance of the thermodynamic systems, reduce the pollutants emission to the environment, and decline the fuel utilization, waste heat recovery methods are in high interest. In this paper, a new configuration of an integrated solid oxide fuel cell and gas turbine combined with a biogas reforming cycle is presented for the cogeneration of power and hydrogen. The thermal energy discharged from the SOFC-GT system is used to supply the energy required for the reforming reaction in the biogas reforming cycle for hydrogen production. Comprehensive thermodynamic and thermoeconomic modeling has been performed using EES software. Also, a parametric study has been performed to demonstrate the effect of different parameters on the main performance metrics of the devised system. The results revealed that the energy efficiency and exergy efficiency of the proposed combined system have increased compared to the SOFC-GT system by 23.31 % and 28.19 % , respectively. The net output power and hydrogen production rate are obtained by 2726 kW and 0.07453 kg / s , respectively. From the exergy viewpoint, the afterburner causes a considerable amount of exergy destruction for the system by approximately 26 % of the total exergy destruction rate. Besides, the sensitivity analysis revealed that by increasing the inlet temperature of the fuel cell, the cell voltage reaches a maximum value at a temperature of 679 K and then decreases. Moreover, the total exergy destruction rate and SUCP of the cogeneration system is calculated by 1532 kW and 9400 $ / GJ , respectively.

A novel power generation plant was devised based on the biomass integrated fired combined cycle as the central unit and supercritical CO2 cycle, regenerative organic Rankine cycle, and steam Rankine cycle as the waste heat recovery subsystems. Exergoeconomic and economic criteria were defined to evaluate the feasibility of the system for investment and construction. Thus, net present value, payback period, and sum unit cost of products were considered as the system’s evaluation criteria from the economic viewpoint. The system was firstly analyzed by developing a precise model in the Engineering Equation Solver. Then, optimal conditions were obtained by coupling the outputs of modeling procedure with artificial neural network, multi-objective particle swarm optimization, and the technique for order of preference by similarity to ideal solution (TOPSIS) approaches. It was concluded that the system has an exergy efficiency of 42.7 % with a power generation capacity of 7.768 MW, a total cost rate of 34.79 $/GJ, and a total profit and payback period of 23.3 $M and 5.7 years. For the optimization results in the e-NPV-SUCP scenario, the optimum values of 58.99 %, 30.6 $M, 35.61 $/GJ were obtained for exergy efficiency, NPV, and SUCP, respectively.

Internal combustion engines consuming fossil fuels produce roughly one-quarter of the world’s anthropogenically generated power. In automobiles, over 50% of the fuel’s energy is dissipated as waste heat. Exhaust heat and jacket water heat are good candidates for waste heat recovery applications. To recover reusable energy from exhaust gases and coolant, water-steam-assist technology has been proposed and established based on an in-cylinder steam-assisted cycle. In this paper, typical water-based waste heat recovery technologies are reviewed and analysed, including the Rankine, Kalina and trilateral cycles. Relevant studies on water-steam-assist implementation are reviewed, and a novel thermodynamic cycle named the in-cylinder steam-assisted cycle is proposed based on their common features. The main characteristics of this cycle are compared with those of previous techniques in terms of principles, parameters, merits and demerits, and development trends. The analysis shows that water-steam-assist technology has the potential to increase engine efficiency considerably. This work helps elaborate the utilization of this waste heat recovery technology in automobiles and provides a comprehensive overview of its mechanisms.

Cogeneration systems based on internal combustion engines (ICE) provide decent efficiency and flexibility. In order to further improve the efficiency, organic Rankine cycle (ORC) can be used to convert high temperature (waste) heat from flue gas to electricity. There is a large amount of heat in jacket cooling at lower temperatures for which there is often no demand so it has to be rejected into the ambient. Previous systems trying to utilise this heat in the ORC cycle end up as too complex and expensive. This study introduces an innovative jacket cooling method. In the cooling system of an ICE, instead of typical water or oil-based heat transfer fluids, the working fluid of an ORC is used as the engine coolant, recovering the low-potential heat. Preheated organic fluid is then directly used in the bottoming ORC with further heat input from the flue gas. This concept allows utilising both low and high potential heat from the cooling of the ICE and from the flue gas recovery, while omitting the intermediate heat-transfer circuits commonly found in ORC waste heat recovery applications. Presented thermodynamic analysis shows a strong dependency of the ORC utilisation efficiency on cooling fluid allowed pressure in the ICE jacket and on the heat flow ratio between the coolant and the flue gas of the ICE. A baseline study with a specific 83 kWe ICE with the novel configuration provides an improvement of nearly 10 kW in comparison with 7 kW of an ORC utilising only flue gas. More general parametric analysis has shown the potential of the ORC power output improvement by more than 60% for specific ICE types and higher pressures and temperatures in the engine cooling circuit. In a cogeneration regime, these benefits in electrical power output come at the cost of a very slight decrease in overall efficiency.

The cement industry has the highest proportion of energy consumption and greenhouse gas (GHG) emitted in the Thai demand-side industry sector. Therefore, the potential GHG emission from energy efficiency is necessary to achieve the NDC target. Due to vast thermal energy consumption for cement production, especially clinker production, waste heat recovery utilization for power generation which partially replaced the on-grid electricity for cement production, has been estimated the GHG emission performance tracking in this study. We found that there are 12 waste heat power plants with a total 263.5 MW installed capacity in the Thai cement industry. With a potential of 1,663,674.21 MWh electricity production annually and GHG mitigation potential of 793,572.60 tons CO2eq per year in 2019. This GHG mitigation figure accounts for 7.21% of GHG mitigation targets for the NDC roadmap.

Diesel engine has been used as the primary mover in vehicles for a long time. It is known that around 25%–30% of the fuel energy is wasted in the exhaust gas from diesel engines. In this study, a turbine power generation system including a 1.8 kW 60,000 r/min high-speed permanent magnet generator and a micro exhaust gas turbine, which is coupled to a diesel engine is designed and modeled to investigate its potential for recovering the wasted energy in the exhaust gas from a diesel engine. Computational models are set up using GT-POWER, MATLAB/SIMULINK and ANSOFT software. The performance and characteristics of the generator, the exhaust gas turbine and the engine are investigated. The simulation results showed that the exhaust turbine power generation system recovered the energy from the engine exhaust gas to generate electrical power. Simultaneously, the maximum power generated is 1.8 kW when the turbine speed is 60,000 rpm. The system efficiency reached its peak of 42.8% when the engine speed is 3000 rpm Last but not least, the electromagnetic characteristics of high-speed permanent magnet generator, which is coupled to an exhaust turbine, are also discussed and presented.

Membrane-based absorption cycle is a novel technology to provide excellent heat and mass transfer performance in the main components for the convenience of small-scale applications. An overview is provided to summarize its progress and gives insights and possibilities for future development. A development trends analysis shows that the membrane-based absorption cycle is an emerging technology and attracts increasing attention in recent decades. Plate-and-frame module and hollow-fiber module are two common membrane-based modules that can improve the heat and mass transfer of absorber, desorber, and solution heat/mass exchanger. Besides, integrated components, including integrated evaporator-absorber and integrated condenser-desorber, have been proposed for further system size reduction. A thorough review of the cycle configurations indicates that the closed-type membrane-based absorption cycles could provide stationary cooling or heating capacity with better cycle performance, while the open cycles are more suitable for waste heat recovery and gas dehumidification. Apart from the conventional H2O–LiBr and NH3–H2O working fluids, ionic-liquid-based mixtures are promising candidates to overcome the existing constraints. But they also face some shortcomings, including high cost and possible high viscosity. This work is expected to facilitate the development and application of the membrane-based absorption cycle towards compact and efficient renewable/waste energy utilization.

The roller kiln is characterized by significant heat losses mainly caused by flue gas and cooling gas accounting for 70%. In this study, four novel power cycles including a basic organic Rankine cycle (BORC), a regenerative organic Rankine cycle (RORC), a Kalina cycle11 (KC11) and a Kalina cycle 34 (KC34) with the parallel double-evaporator (PD) configuration are proposed for dual-level waste heat recovery for a roller kiln. To identify the superiority system, the recommended power cycles are assessed and compared from an integrated thermodynamic and economic perspective. The impacts of the basic operating parameters on net power output, exergy efficiency, electricity production cost and savings to investment ratio are discussed. Meanwhile, the single-, bi- and three-objective optimizations are conducted and the optimal solutions are compared. The results indicated that for the considered optimization models, PDKC34 achieved the highest net power output of 211.06–224.45​ kW and thermal efficiency of 20.02–21.20%, PDBORC had the best economic performance on electricity production cost of 0.0875–0.0932 $/kWh, payback period of 5.709–6.210 year and savings to investment ratio of 2.191–2.335 while PDRORC with R-141b possessed the best exergy efficiency of 45.11–49.17%. On the whole, the four thermodynamic cycles contributed to the best thermodynamic performance in the maximizing net power output model while these had the best economic performance in the minimum EPC model. Besides, the evaporation unit had the highest impact on exergy destruction and total investment cost among all components for the studied optimization models.

Three novel geothermal-based organic Rankine cycle (ORC) systems are proposed to enhance the efficiency and for waste heat recovery purpose. The proposed systems are modeled based on a basic ORC system (concept 1), an ORC system with an internal heat exchanger (concept 2), and a regenerative ORC system (concept 3). Accordingly, two thermoelectric generators (TEG) are introduced into the systems to exploit the waste heat of the system. The condenser is replaced with a TEG unit while the other TEG unit is used to recover the waste heat of the reinjected geothermal fluid. A comprehensive numerical investigation is conducted to compare the proposed systems from the thermodynamic and thermo-economic points of view. Furthermore, the most favorable proposed system is considered for optimization purposes and multi-objective optimization using the genetic algorithm is performed. Accordingly, a Pareto frontier is extracted consisting of the optimal solutions along with the scatter distribution of the critical parameters. The results indicate that the third proposed concept holds the highest exergy and energy efficiency among the studied systems. Also, the concept concludes the highest power output from the employed TEG units. The results further show that the first concept has the lowest associated cost with the system and the smallest payback period and at the same time higher net power generation. At the baseline of the systems, the exergy efficiencies are 59.39%, 57.92%, and 60.27%, and the total product costs are 25.8 $/GJ, 28.79 $/GJ, and 31.27 $/GJ for the first, the second, and the third proposed concepts, respectively. Results of the multi-objective optimization of the third concept reveal that the superheater temperature difference should be kept at higher values while the optimal range of the figure of merit is between 0.9 to 1.6. The proposed systems can be designed practically to exploit the geothermal heat source and recover the waste heat of the system.

The waste heat recovered by traditional industrial waste heat recovery systems is mostly high-temperature flue gas and combustible gas, while the waste heat of medium and low temperature flue gas that accounts for more than 50% of the total waste heat resources has been ignored, which is not conducive to the effective energy saving of industrial production and manufacturing process. In the meantime, few studies have concerned about the changes in the economy of circulating industrial waste heat recovery system. Therefore, to fill in this research gap, this paper aimed at the economy problem of circulating medium and low temperature industrial waste heat recovery system and carried out a series of research. The paper completed the thermodynamic analysis of different medium and low temperature waste heat recovery modes of industrial flue gas, and gave the analysis steps of the economy of circulating medium and low temperature waste heat recovery system of industrial flue gas. The effectiveness and accuracy of the thermodynamic and thermo-economic models constructed in the paper were proved by experimental results.

All-fresh-air heating, ventilation, and air conditioning systems with high air exchange rates are typically applied in conventional laboratory animal houses (LAHs), resulting in high energy consump...

The ever increasing demand for energy has necessitated exploring innovative techniques for low and medium temperature energy extraction. Among them, Kalina cycle is considered efficient for extracting energy from low grade renewable sources like solar, geothermal and for waste heat recovery. In this work, we propose a Kalina cycle with turbine staging and heating between the stages. A case study is presented to illustrate the cycle. The cycle is analysed for varying pressure in the second separator and mass fraction of vapour from the first separator. The dependency of variables on separator temperature, vapour fraction at the turbine exit, net work output of the cycle, net heat input of the cycle and efficiency are analysed. Optimisation of efficiency with second separator pressure and mass fraction of vapour at the first separator as variables has been carried out using Genetic Algorithm. The optimised efficiency for the illustrative example shows an improvement of 4% compared to a simple Kalina cycle with same input parameters.

The increased use of fossil fuels in the industry has resulted in severe environmental issues, such as ozone depletion, air pollution, and climate change, among others. Due to diverse resources, su...

The process of achieving decarbonization and greenhouse emissions’ reduction goals is facilitated and accelerated by the implementation of renewable-based DH rather than multiple individual renewables systems. This work presents an application case that demonstrates how an energy system based on conventional and carbon-emitting heat supply sources can be converted in a fully renewable network. In its current configuration, the city under study, located in Northern Italy, gets 40% of the total 160GWh of heat demand of the DH from a waste-to-energy plant, 9% from a biomass-fuelled ORC, 33% from natural gas cogeneration and 18% from natural gas boilers. In order to support the city’s municipality in developing decarbonization measures through the modernization of the current district heating network, the aim of this work is to investigate in detail the possibility to integrate local renewable and excess heat sources, whose availability and synergy with the heat demand has been highlighted by a recent mapping-based project developed with the Italian DH Association, AIRU, on the whole Italian territory. The present work can be therefore seen as a validation case study of the methodology developed at large-scale level in the latter project. The results of that analysis show that there are the conditions to meet 90% of the heating needs of the DH with renewables and waste heat recovery from two already existing plants, namely a wastewater treatment plant (WWTP) and a steelwork. The approach used in this work, in which different scenarios of integration are simulated in energyPRO, brought to the definition of the energy mix which evidenced a favourable cost–benefits ratio: 59% of thermal energy from the steelwork, 31% from the WWTP, 5% from the natural gas CHP and 5% from the boilers.

Waste heat recovery along with low-grade energy can be utilized for numerous applications in our daily life. This manuscript presents a novel idea of utilizing the waste heat from domestic cooking devices for assisting the solar desalination system through simulation and validated experimentally. To assess the potential of waste heat from a 2D axisymmetric model of water jacket has made using ANSYS Fluent while applying the user-defined function (UDF) to the outermost wall of the cookstove having the temperature as high as 340 °C during the operation. Further, to ensure the recovery of the waste heat, without affecting the performance of the cookstove, an air gap of 0.05 cm was provided between the combustion chamber and the water jacket. The efficiency of the original cookstove without air gap was found to be ~ 33%, which enhanced up to ~ 43.79% without flow of water in the jacket, and finally reached up to 56% when water flows in the jacket. This indicates that the arrangement used in this particular study has not only recovered the waste heat but also improved the overall performance by ~ 69.34%, without disturbing the cooking phenomenon. Supplementary Information The online version contains supplementary material available at 10.1007/s40095-021-00430-z.

Despite the massive electrification of the energy sector, combustion-based technologies will continue to play a key role for decades to come. Therefore , to meet the ambitious target of decarbonization of the energy sector, adapting current technologies to alternative energy sources, like biofuels, is a must. The proposed work aims at investigating the role of biomass producer gas in compression ignition (CI) engines, as a substitute of diesel fuel. A micro combined heat and power generation system (CHP) consisting of an open-top downdraft gasifier, a single-cylinder water-cooled CI engine and a waste heat recovery circuit have been set-up with the aim to investigate emissions and performance at several Diesel Substitution Rates (DSR), up to 50 %. Maximum substitution levels – which occur due to knocking limitations and combustion instabilities - have been also identified. The main results show: i) a decrease of thermal and electrical efficiencies in the range of 10–30 %; ii) strong NOx and smoke opacity reductions (with peaks close to 80 %); iii) an increase of CO emissions (above 50 %); iv) the assessment of a decreasing maximum DSR as the power load increase (98 % at the lowest load, up to 46 % at full load). Such findings offer quantitative results through which multi-objective optimization procedures could be implemented. Moreover, experimental results indicate the need for a diesel injection timing optimization strategy to mitigate CO emissions.

In coal-fired power plants, most of the working fluids used in a mid–low-temperature flue gas waste heat recovery system (FGWHRS) are low-temperature boiler supply air or condensate water in the flue gas condenser. This is prone to cause low-temperature corrosion, as the system temperature is lower than the acid dew point of the flue gas. In this study, an experimental apparatus was set up at the entrance of the desulfurization tower of a 330 MW unit in Xinjiang, China, which uses the technology of high-temperature boiler feed water (above 80 °C) to recover the waste heat of mid–low-temperature flue gas. The heat exchange performance of the mid–low-temperature FGWHRS was evaluated under different working conditions, and the optimal input parameters of the system for each considered working condition are given based on the analysis. It was found that the low-temperature corrosion in the system could be avoided using this technology. To eliminate low-temperature corrosion, the lowest temperature for the inlet water was predicted to be 69 °C in our study via curve fitting based on the experimental data. The results could provide a theoretical basis and engineering guidance for determining the best heat recovery strategy of mid–low-temperature FGWHRS.

Heat recovery technology using thermoelectric has attracted many research intentions mainly for its ability to generate power passively. The automotive engine usually produces waste heat ranging from 30-40% due to the thermodynamic limit. The use of thermoelectric generator (TEG) for waste heat recovery and power generation could increase the efficiency of the internal combustion engine system. This research developed and investigated a heat recovery system using a thermoelectric generator (TEG) for power generation. A thermoelectric generator (TEG) consisted of thermoelectric modules, hexagonal pipe connector and heat sinks was built and connected to an exhaust pipeline. A theoretical model was developed to access the thermal and electrical performance of the TEG system. The theoretical model consisted of the heat transfer mechanism including the thermal resistance networks from the flue gas to TEG and the heat sink. The electrical power output was determined using the Seebeck principle. The early stage of finding reveals that the system was able to produce an open circuit voltage of 0.13 V for a small temperature gradient of 3ᵒC between the cold and hot surface of the TEG. The further improvement of the system is currently under investigation for producing higher power. In the future, this system hopefully could replace the car battery for charging the alternator as well as increasing the overall efficiency of the engine system.

Worldwide, motorcycle sales have increased significantly during the coronavirus disease 2019 pandemic process. Thermoelectric generators are technologies that can directly convert waste heat into electrical energy in internal combustion engines. In this study, a waste heat recovery system with a thermoelectric generator has been designed for the exhaust system of a motorcycle engine with a cylinder volume of 50 cc. The performance of the waste heat recovery system has been examined under throttle opening of three-fourth and at different speeds, and a thermal model of the system has been created by means of the GT SUITE model. According to the test results, the increase in engine speed caused different temperature differences on the surfaces of the TEG module due to the constant flow of the fan the maximum recovery power has been found as 2.05 W at an engine speed of 6000 r/min and the maximum system efficiency has been found as 2.41% at an engine speed of 4000 r/min. Following minimum temperature differences have been calculated between experimental and GT SUITE thermal model calculations: 14.05 K at an engine speed of 4000 r/min and at [Formula: see text] temperatures; 14.1 K at an engine speed of 6000 r/min and at [Formula: see text] temperatures; and 7.5 K at an engine speed of 5500 r/mi and at [Formula: see text] temperatures.

In a variety of waste heat utilization technologies, absorption refrigeration can be driven by low-grade heat to provide cooling capacity, which is suitable for situations with both waste heat supply and refrigeration demand. In this paper, an ammonia-water absorption refrigeration prototype with a new generator structure is experimentally studied. Its economic analysis is carried out for pre-cooling in a liquefied natural gas plant. It is investigated that 1.8 kW cooling capacity at −10 °C is obtained, COP maintains between 0.29 and 0.35, and waste heat recovery ratio is improved by 150%. The proposed system is applied to a 30,000 Nm3 d−1 liquefied natural gas plant to replace the conventional compression refrigerator as the pre-cooling stage, and waste heat from exhaust gas and jacket coolant is recovered in the reboiler and stripping section, respectively, in order to provide cooling capacity for pre-cooling of both natural gas and refrigerant. Economic analysis shows that specific power consumption of the modified system is reduced by 30%, from 0.40 to 0.28 kWh Nm−3. Consequently, the annual natural gas consumption and operating costs are reduced by 17.3% and 9.4%, respectively, and the payback period is 2.2 years compared to conventional systems with compressor-based pre-cooling stages.

The present study develops a novel energy system comprising a double-flash based geothermal cycle, a solar-driven cycle, a polymer electrolyte membrane (PEM) system and a waste heat recovery system. The proposed system can be used to generate electricity, produce hydrogen, space heating and prepare domestic hot water, and the solar-driven cycle can be turned off as a double-flash geothermal system when there is no solar radiation and the storage is empty. The unique aspect of the proposed system lies in the coupling relationship between the three turbine units in clear weather. Energy and exergy analyses are carried out to determine the irreversibilities, show the performance of the system and compare it with sole geothermal system. The results show that the proposed system has satisfactory thermodynamic properties. Under the reference conditions, the proposed energy system has a 148.3% (from 6171 kW to 15321 kW) increase in power generation compared with a sole double-flash geothermal system; under the optimal working conditions, the energy efficiency and exergy efficiency of the system can reach 29.6% and 29.2%, respectively. Furthermore, the effect of changing various system parameters on the energy and exergy efficiencies of the entire system and its subsystems were also studied.