Exhaust Waste Research Articles

Green Extraction Techniques for Obtaining Bioactive Compounds from Mandarin Peel (Citrus unshiu var. Kuno): Phytochemical Analysis and Process Optimization.

In this study, an efficient utilization and valorization of mandarin peel (Citrus unshiu Marc. var. Kuno) was investigated using innovative and green extraction techniques. The first step of this study included the extraction and analysis of the volatile compounds by performing a supercritical CO2 (SC-CO2) extraction under different operating pressure conditions (100 and 300 bar). The analysis of volatile compounds of the obtained extracts was conducted by gas chromatography-mass spectrometry (GC-MS), and limonene was found to be the dominant volatile component (13.16% at 100 bar; 30.65% at 300 bar). After SC-CO2 treatment, the exhausted citrus peel waste enriched with bioactive compounds was subjected to subcritical water extraction (SWE) in a wide temperature range (130–220 °C) using different solvent-solid ratio (10–30 mL/g) in time periods from 5 to 15 min, in order to obtain bioflavonoids. Identification and quantification of present bioflavonoids was conducted by high-performance liquid chromatography with a with a diode array detector (HPLC), and hesperidin (0.16–15.07 mg/g) was determined as the most abundant flavanon in mandarin peel with other polyphenolic compounds that were possible by-products of thermal degradation. At higher temperatures, the presence of 5-hydroxymethylfurfural (5-HMF) and chlorogenic acid were detected. Antiradical activity and total phenolic content in the extracts were determined using spectrophotometric methods, while the process optimization was performed by response surface methodology (RSM).

Energy Saving and Economic Evaluations of Exhaust Waste Heat Recovery Hot Water Supply System for Resort

The objective of this study is to investigate the energy savings and economics of the hot water supply system for the luxury resort. The hot water was generated using the waste heat from the exhaust gas heat (EGH) of internal combustion engine (ICE) installed at the luxury resort. The capacity and characteristics of waste heat source, flow demand and supply system of hot water were surveyed, and data is collected from the real system. The new heat exchanger system which utilizes the EGH to produce the hot water is designed considering the dew point temperature and the back pressure of exhaust gas system. The results show that the proposed system could supply hot water at a temperature of 55 °C corresponding to the present resort demand of 6 m3/h using EGH of ICE at 20% load. The proposed system could achieve the saving of 400 L/day in diesel oil (DO) fuel consumption and the payback time of new system could be evaluated as 9 months. The proposed system could produce hot water of 14 m3/h at 25% of engine load and 29 m3/h at full engine load which are sufficient to satisfy the regular and maximum hot water demand of resort. The presented results show the capability of the proposed system to satisfy the current hot water demand of resort and suggest the larger potential to save energy by recovering EGH of ICE. The novelty of the present work involves detailed methodology to design heat exchangers and evaluate system economics for hot water supply system based on EGH of ICE.

Catalytic oxidative desulphurization of pyrolytic oils to fuels over different waste derived carbon-based catalysts

In this work, we reported the conversion though carbothermal process of two catalysts produced by pyrolyzing exhausted coffee and waste tires. We tailored the surface with anchored iron nanoparticles through a facile carbothermal route and tested them for catalytic oxidative desulphurization of high sulphur content oil derived from tires pyrolysis. We studied their activity in a biphasic system under different conditions reaching a desulphurization of up to of 60% by using an oil with a sulphur concentration of up to 7139 ppm. The extensive characterization proved the reliability of those materials as promising catalysts for upgrading of sulphur rich drop-in fuels.

Vapor-compression refrigeration system coupled with a thermochemical resorption energy storage unit for a refrigerated truck

Currently, refrigerated trucks adopt vapor-compression refrigeration systems for controlling the temperature of refrigerating compartment. This inevitably increases fuel consumption and exhaust emissions of engine. Although the solid sorption refrigerator can recover exhaust waste heat to generate cooling capacity, the low exhaust temperature at idle, often below 150 °C, significantly restricts its application in refrigerated trucks. To tackle these problems, a novel refrigeration system, including a vapor-compression subsystem and thermochemical resorption energy storage unit, using MnCl2/CaCl2-NH3 as the working pair, is proposed in this paper. To date, this is the first study wherein the system performance test is conducted on a refrigerated truck. Experimental results indicate that thermochemical energy storage can effectively recover waste heat of exhaust gas to store cold energy, and the refrigerating capacity during the discharging process is 2.2 kW at an evaporator outlet temperature of −15 °C. Moreover, cold energy can be released irrespective of whether the truck is parked or driven. Measurement of the liquid level in the liquid reservoir is an effective method for determining the point at which the operation switches between energy discharging and charging processes. At an ambient temperature of 30 °C and a refrigerating temperature of −20 °C, the energy efficiency of the novel system is 1.4, which is twice that of a conventional system. Furthermore, although energy storage increases initial investment of system, the payback period is estimated to be less than one year. In conclusion, the novel system effectively reduces transportation costs and satisfies the requirements of refrigerated trucks in a stable manner.

A non-linear systematic grey model for forecasting the industrial economy-energy-environment system

To estimate the internal structure and forecast dynamic trends in the industrial economy-energy-environment (3E) system, a non-linear systematic grey model (NSGM(1, m)) is proposed. This model is derived from a non-linear grey Bernoulli model (NGBM(1, 1)) and consisted of multiple non-linear equations in an embedded manner. To minimise the mean absolute percentage error (MAPE), a particle swarm optimisation (PSO) algorithm is used to optimise the parameters of the model. The empirical analysis based on a dataset of Zhejiang Province, China from 2000 to 2018 shows that the NSGM(1, m) model can identify a non-linear relationship among industrial economic growth, energy consumption, and pollutant emissions. The MAPEs of training sets of three industrial 3E systems are 2.95%, 4.90%, and 3.75%, while those of test sets are 1.36%, 6.94%, and 1.72%, respectively. From 2019 to 2023, it is predicted that, with constant industrial and economic growth, industrial energy consumption and discharge of exhaust and solid waste will continue to increase while industrial wastewater discharge will decline. Moreover, efficiency indices indicate that the economic efficiency of the industrial 3E systems in Zhejiang Province will increase.

Enhancing induced flow rate through a solar chimney by a forced flow

Solar chimneys absorb solar radiation for natural ventilation or cooling of buildings. In typical solar chimneys, the air flow is induced by the thermal effect which causes pressure gradient inside the chimney to deviate from that of the ambient air. The induced flow is employed to ventilate the connected building naturally. In this study, we aimed to boost the induced flow rate through a typical solar chimney by a forced flow at the inlet of the air channel which is divided into two ports for the forced and the induced flows. The air flow and heat transfer were modeled with a Computational Fluid Dynamics (CFD) model with the ANSYS Fluent CFD code. Changing factors included the forced velocity, the dimensions of the inlet port for the forced air flow and the length of the partition between the ports of the naturally induced and forced air flows. It is seen that the forced flow significantly reduces the pressure in the air channel compared to that of a typical chimney; hence increasing the induced flow rate. The flow rate was significantly enhanced as the forced velocity was above 0.2 m/s; the area of the inlet port for the forced flow was 12.4% of the total inlet area; and the partition height was less than 5.0% of the total height of the air channel. In this configuration, the forced flow can be the waste exhaust air flow from other mechanical ventilation systems of the building. Therefore, no additional energy is required for this solution.

Multi-objective optimization of a novel offshore CHP plant based on a 3E analysis

Recovering waste heat of gas turbines in order to power production and heat supply is one of the effective approaches in energy and environment management in offshore installations. In the present study, a gas turbine in the Draugen offshore platform was modeled and its exhaust waste heat was utilized to generate power through an ammonia-water cycle and supply the heat demand of the offshore facility. In order to optimize the combined heat and power system, pressure ratio, maximum temperature of gas turbine, heat source temperature of bottoming cycle, ammonia mass fraction, and boiler pressure were considered as the effective decision variables. At first, based on each of the objective functions including exergy efficiency, rate of carbon emissions, and payback period, the operating conditions were optimized by a genetic algorithm. Finally, the results of a multi-objective GA optimization were presented in which all three objective functions were simultaneously optimized. Based on the multi-objective function, the optimum values of pressure ratio, maximum temperature of gas turbine, heat source temperature of bottoming cycle, ammonia mass fraction, and boiler pressure were 21.94, 1359K, 605K, 37.73 bar, and 88.2%, respectively.

Simulation of exhaust gas energy recovery system using turbocompounding for a motorcycle engine

The project aims to recover the energy from the waste exhaust gas and utilize it for application such as battery charging of hybrid electric vehicles. The concept used for energy recovery is electric turbo-compounding which encompasses a turbine integrated with the exhaust manifold of an automobile. The exhaust gases are allowed to expand through the surface of blades of the turbine imparting the energy which can be seen by rotational action of impeller. This motion is captured by a motor generative unit which then produces electric power. The performance of the exhaust gas energy recovery system is simulated on a 390cc motorcycle engine using MATLAB Simulink. The engine was simulated using standard practical low loading and high loading drive cycles such as FTP72, FTP75 (city driving cycles) and US06 (highway driving cycle). Results from the simulation indicate a considerable amount of energy recovery from the exhaust gases of an engine under the above-mentioned driving cycles. Considering the amount of energy recovered, the next focus is to optimize the current system.

Experimental study on exergy and sustainability analysis of the thermoelectric based exhaust waste heat recovery system

Experimental study on exergy and sustainability analysis of the thermoelectric based exhaust waste heat recovery system

Thermodynamic analysis of exhaust waste heat recovery from turbocharged HCCI engine fueled by wet-ethanol using an absorption refrigeration cycle (ARC)

This paperpresents a thermodynamicstudy of the exhaust waste heat recovery from turbochargedHomogenous Charge Compression Ignition (HCCI) enginepowered by wet-ethanol for a combined output of engine power and cooling system by using a LiBr-H2O absorption refrigerationcycle (ARC). For power production, an HCCI engine has been used, and an ARC driven by engine exhaust heat has been used as a bottoming cycle for refrigeration. While varying the compressor pressor ratio, compressor efficiency, and ARC generator temperature, the thermal and exergetic performance of the combined power and coolingcycle was investigated. The results showed that increasing the compressor ratio (2.25–3.75), and efficiency of the compressor (0.725–0.875), increases HCCI engine power and increases the cooling of the bottoming cycle. As a result, both thermal and exergeticefficienciesof the HCCI engineandcombined cycle increase. In addition, as the temperature of the generator (361–385 K) rises, the ARC's thermal and exergetic COPs decreases.

A numerical study on processes of charge and discharge of latent heat energy storage system using RT27 paraffin wax for exhaust waste heat recovery in a SI engine

In the present paper, the numerical analyses of the heat charge and discharge processes of the latent heat energy storage (LHTES) system designed for the recovery of the exhaust waste heat energy of the SI engine presented. In the LHTES system as phase change material (PCM), the charge and discharge ability of paraffin wax commercially identified with code RT27 were analyzed depending on time. Two closed-loop fluid circulation system consisting of two heat exchangers (HESs) was designed, someone connected to the exhaust path of SI engine for waste heat recovery, and the other used for the charging and discharging of waste heat energy in the PCM. To transfer the waste heat from the hot exhaust gases to the PC, cold water was used as the heat carrier fluid. In the numerical analysis, the exhaust gas temperature and flow rate values of a single-cylinder, air-cooled having a stroke volume of 476.5 cm3 SI engine operated with gasoline at 1600 rpm engine speed and 1/2 throttle position were used. As a result, at designed LHTES system and numerical analysis performed for RT27 paraffin wax under boundary conditions, the process of heat charge (melting) completed at 8000.sec with 93% liquid-fraction, while the process of heat discharge (solidification) completed at 55000.sec with 15% liquid-fraction.

Thermoelectric performance of an exhaust waste heat recovery system based on intermediate fluid under different cooling methods

Thermoelectric generators (TEGs) can effectively recover waste heat from the exhaust of automobiles and generate electricity. An intermediate-fluid TEG system is based on the vaporization and condensation of an intermediate medium, exhibiting high-efficiency thermoelectric conversion. In this study, a mathematical model of an intermediate-fluid TEG system is established, and the influences of cooling methods and condensed-boiling heat transfer performance in the cavity on the thermoelectric performance are analyzed. The results show that the new generator exhibits better characteristics than the traditional TEG system under both water-cooling and air-cooling methods. We not only improved the power output, but also reduced the optimal thermoelectric module area under the water-cooling method. Moreover, the condensation heat transfer coefficient in the cavity had a significant effect on the power performance of the proposed system. The boiling and condensation heat transfer coefficients should both remain greater than 5000 W/m2K for a high efficiency of the TEG. This work provides guidance for the design of new TEGs and high-efficiency utilization of exhaust.

Experimental study on exergy and sustainability analysis of the thermoelectric based exhaust waste heat recovery system

In the present study, the energy and exergy analysis of a thermoelectric based waste heat recovery system of a passenger automobile is performed at different loads. Further, an exergetic sustainability assessment is performed by incorporating parameters like exergy destruction factor, environmental impact factor and exergetic sustainability index. Results revealed that by employing waste heat recovery, the exergetic efficiency can be improved by up to 5.78%. The study showed that the exhaust gas is more suitable for heat recovery as it has 81.8% more exergy than the cooling water.

Thermodynamic assessment and proposal of new configurations of an indirect water bath heater for a City Gate Station (a case study)

This paper deals with thermodynamic modeling and proposal new configurations of an indirect water bath heater used in a city gate station (CGS) to preheat the natural gas (NG). In the transmission pipeline of natural gas before reducing NG pressure, it is necessary preheating to prevent hydrate formation. In the traditional systems, an indirect water bath heater is used for this purpose. Thermodynamic modeling of the proposed systems has been done in EES software, and an effective analysis based on proposed new configurations is conducted. The results indicate that using exhaust combustion products to preheat the combustion air can increase the thermal efficiency of the system from 46.36% (for base case) to 73.84%. In addition, with the use of an ORC to utilize the exhaust waste thermal energy, the system efficiency of 55.27% with an electrical output of 79 kW can be achieved. A comparison between configurations indicates that the second configuration (preheating combustion air) with 78.97 kg/h has the lowest emission rate.

Waste heat recovery in commercial gas-fired tumble dryers

Thermal drying is energy intensive due to the unavoidable thermodynamic constraint of supplying sufficient energy to evaporate the water (hfg > 2000 kJ kg−1). Textile dryers only use about half (∼55%) of the total input energy for drying. To reduce the wasted energy, exhaust gas recirculation and waste heat recovery using a recuperative heat exchanger are investigated numerically and experimentally. The two methods aim to recover energy from the exhaust stream typically at T < 55 °C for most of the drying period. Experiments are conducted on a commercial gas-fired tumble dryer. A theoretical model is developed to simulate and optimize the drying process. Recirculating the hot humid exhaust gases improves heat and mass transfer in the drum; however, the high humidity ratio of the recirculated air is not amenable to enhancing evaporation. An optimal recirculation ratio of 51% is found to reduce the specific moisture extraction ratio and drying time by 9% and 164 s, respectively. To avoid the rise in humidity associated with recirculation, a compact plate-fin heat exchanger is used to recuperatively preheat the air entering the combustor. Energy savings of ∼15% and reduction in drying time by 216 s over the baseline case are estimated. The predicted data demonstrate good agreement with experiments.

Design and analysis of a novel dual source vapor injection heat pump using exhaust and ambient air

• A novel dual source vapor injection heat pump is designed and analyzed. • It is first attempt to recover ventilation heat by a vapor injection compressor. • A waste heat recovery rate of more than 100% is achievable. • It has a COP of 23.2% higher than a conventional air source heat pump. • The largest exergy destruction takes place in the compressor. 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.

Optimization of the integrated power and desalination plant with algal cultivation system compromising the energy-water-environment nexus

This article examines the exhaust waste heat recovery potential of a microturbine (MT) for seawater desalination using an organic Rankine cycle (ORC). Waste heat from microturbine is exploited using organic Rankine cycle (ORC) and the power generated is delivered to the reverse osmosis (RO) plant. The brine of the reverse osmosis plant is sent to a membrane distillation (MD) plant for further treatment after preheating using the excess heat from the turbine. Also, biological capture of CO2 through cultivation of microalgae has been considered by using flue gases from the microturbine. Plant integration is performed on the basis of the energy-water-environment nexus concept. In this regard, a multi-objective optimization approach is implemented in this work considering economic and environmental points of views. The first objective function is to maximize the annual profit of the system. The second objective function is an environmental index which is defined as the CO2 emission per desalinated water production. Minimization of this index is considered as the second objective function. The results showed that the proposed integrated ORC-RO-MD-CO2 capture plant can considerably improve the system both economically and environmentally.

Exhaust waste energy recovery using Otto-ATEG-Stirling engine combined cycle

In the present study, using the Stirling cycle and thermoelectric modules, the exhaust heat dissipation of a gasoline engine was recovered. In this regard, a gasoline engine, a Stirling engine, and a commercial thermoelectric module were first modeled and validated. In order to benefit from the Stirling engine along with the gasoline engine, it was necessary to redesign the Stirling engine heater to suit the needs of the project. The designed heater is a shell and tube heat exchanger, and on its shell, there are places to install thermoelectric modules. In Ansys CFX software, the performance of this heat exchanger was analyzed and its performance was evaluated. The results illustrated the maximum pressure drop is about 2.63 mbar. Also, the net power generated by the module set is in the range of 223–528 W, and the Stirling engine power for the temperature range of 358 °C − 535 °C was reported to be 1.8–6.8 kW. In total, the combined cycle power and efficiency increased by about 7% and 2.5% respectively. Finally, the analysis showed that fuel consumption has decreased by about 8% and about 0.7% of this amount was related to the performance of thermoelectric modules.

The feasibility of using a combined heat and power system in a car factory with different consumption and investment scenarios

ABSTRACT Decreasing energy consumption, greenhouse gases, and fuel cost motivate researchers toward using Combined Heat and Power (CHP) systems. Of course, finding suitable scenarios for consumption, sales, and investment is very important in using the CHP system. In some countries like Iran due to the non-consideration of the environmental taxes and low fuel prices implementing the CHP projects is still a challenge. Although the economic and technical benefits of CHP projects are truly registered, the methods of financing are still a dilemma. In the present study, the feasibility of using the gas engine to generate electricity and recovering the exhaust waste heat to supply the required heat of a car-manufacturing plant in northeastern Iran was investigated. The different numbers of gas engines to supply heat and electricity were analyzed. Based on the results, the use of three gas engines supplied more than 75% of the annual required heat of the car factory. Also, two different investment scenarios for attracting investors were proposed. These scenarios improved the conditions to attract the investors via displaying the financing landscapes of the project and providing its detailed information. Considering the results, when the car factory is the investor, the strategy of electricity sales to the grid and exhaust heat consumption in the car factory is the most cost-effective selection.

Production of a biofertilizer from exhausted grape marc waste: agronomic and environmental impact on plant growth

Biochars produced from exhausted grape marc waste were considered a potential source for agriculture biofertilization. Results indicated that the biochar application did not show a significant effect on ryegrass fresh weight increase. The pyrolysis temperature influenced the fresh and dry matter yield since it interferes with phosphorus bioavailability for plant growth. Potassium intakes were positively affected but not statistically significant. The % of soil stable aggregates decreased after 60 days. In the short term, there is no significant effect on soil structural stability. Biochar incorporation led to domination of large macro-aggregates, which are instables compared with small macro-aggregates. A dose of 15 t ha−1 considerably reduced the leached soil and thus improved water retention by changing soil porosity. Soil pH and electric conductivity markedly increased for all treatments after 60 days of incubation. Biochar extract had a significant inhibitory effect on Fusarium oxysporum and Phytophthora sp. The use of exhausted grape marc waste to produce a biochar has shown a good potential for carbon and water sequestration in soil.