High Heat Release Research Articles

Thermochemical sorption heat storage: Investigate the heat released from activated carbon beads used as porous host matrix for MgSO4 salt

For sustainable and cost-effective thermal management and energy storage, sorption-base thermal storage has received a lot of attention. However, the low sorption capacity of sorbents has long been a barrier to high energy-density sorption-based thermal storage. We present a new promising composite with high heat release and sorption capacity. The use of MgSO4/bead activated carbon composites in thermochemical sorption heat storage has been investigated. Because of the highly developed microporosity and high apparent specific surface area of about 1300 m2/g, bead activated carbon (BAC) is a potential candidate as support for salt/support composites for thermochemical heat storage. Also, the thermal conductivity of BAC has been measured and found to be 0.14 W/mK, which is higher than that of other materials like zeolites or alumina. This high thermal conductivity can influence the water sorption equilibrium, controlling the temperature of the solid, avoiding hot-spots, and thus preventing desorption during the hydration step. In stationary conditions (RH = 60 %, gas flow = 30 mL/min), the water sorption capacity of BAC was 0.138 g/g. This value was 2.32 times higher when the salt was dispersed into the BAC matrix, for the composite 7.6-MgSO4/BAC. A water adsorption capacity, higher than the theoretical value, was observed and attributed to the condensation of water molecules within the porous structure, resulting in a high thermal energy density. The 7.6-MgSO4/BAC composite achieved the highest heat of hydration of 920 J/g. The 10 hydration/dehydration cycles performed (dehydration at 150 °C and hydration at 30 °C with a RH of 60 %) confirmed the composite's excellent stability. This research provides a promising low-carbon pathway for the efficient capture, storage, and utilization of thermal energy.

Investigation and optimization of solidification performance of a triplex-tube latent heat thermal energy storage system by rotational mechanism

In this paper, the rotation mechanism is applied to a triplex-tube latent heat thermal energy storage system for the first time. Numerical simulation is used to study the effect of rotation on the solidification performance of this system, and the accuracy of the numerical model is verified experimentally. Firstly, the evolution of the liquid phase, the total amount of heat energy released, and the rate of heat energy released in the solidification process of the thermal energy storage system without rotation and at different rotational speeds are compared and analyzed. It is found that the solidification time of the system at 1 rpm is reduced by 83.85 % and the heat release rate is 4.98 times higher than that at the no-rotation state. It shows that the incorporation of a rotational mechanism can effectively reduce the solidification time and increase the heat release rate of the system. Then, the internal dynamic temperature/flow rate response is used to investigate the change in the heat transfer mode of the solidification process by the addition of rotation and the improvement of the phenomenon of difficult solidification zones, which improved the internal temperature uniformity and thus the solidification behavior. By response surface method, the geometric factors of the heat storage system (fin length, fin width, fin angle) are analyzed by multiple factors. The function of the optimized target (solidification time) on each variable is fitted, and it is found that the fin length had the most significant effect on the optimized target. Finally, the effect of relevant physical parameters on the solidification process and heat release of the thermal energy storage system is investigated. To ensure low solidification time and high heat release rate, this study recommends that the temperature difference between phase change material and tube wall is higher than 25 K. This paper also proves the feasibility and superiority of copper fin/tube wall material.

Fire spread along vertical greenery systems from window ejected flame: A study based on a fire dynamic simulator model

Recent studies have shown that, poorly maintained vertical greenery systems (VGS) have a high fire risk and a tendency to cause very high heat release rates (HRR) in a case of fire. High HRR in materials often results in rapid fire spread in upward orientation. This study used numerical fire simulations with computational fluid dynamics (CFD) to investigate the fire spread along a VGS. The fire simulations were conducted in fire dynamic simulator (FDS) using the pyrolysis model that was specifically developed for vegetation. In FDS, the fire was initiated as a room fire of 1 MW followed by a window ejected flame, which ignited a 12 m tall and 9 m wide VGS. Fire spread along a VGS was modelled with four different moisture contents (MC) and four different packing ratios (PR) of the vegetation fuel bed. The different MCs represented regularly and scarcely watered vegetation, while different PRs represented different bulk densities of the vegetation in the VGSs. The fire spread rate was increased when both the MC and PR were decreased. The rate of fire spread in the upward orientation, which is the most hazardous mode of fire spread, was found to increase by 469.8% when the MC was decreased from 80% to 10%, and by 207.1% when the PR was decreased from 0.5 to 0.1. The results are helpful in understanding the design of a VGS with an optimum level of vegetation density and maintaining the vegetation fresh and alive to minimise the fire hazard. • Numerical simulations are conducted with a fire dynamic simulator model. • Moisture content (MC) and packing ratio (PR) of vegetation were varied. • Lower MC and PR of vegetation increase the fire spread rate. • Fire spread is notably faster in the upward direction over green wall. • Keeping vegetation fresh and lush is vital to reduce the fire risk.

Analysis on the convective heat transfer process and performance evaluation of Triply Periodic Minimal Surface (TPMS) based on Diamond, Gyroid and Iwp

Heat dissipation capacity is one of the bottlenecks in developing high heat release devices such as electronic chips and laser generators. TPMS exhibits good thermophysical properties and is expected to provide better heat dissipation solutions for high heat-releasing devices. However, studies on the convective heat transfer properties of TPMS structures are still insufficient. In this manuscript, research focuses on evaluating the convective heat transfer performance of several representative TPMS structures and elucidating their mechanism of enhanced heat transfer. The TPMS studied in this paper include Gyroid, Diamond, and Iwp, and their convective heat transfer performance is compared with that of Fins-structure. In addition, an experiment was carried out to verify the accuracy of the numerical simulation. The results showed that the numerical simulation results were in good agreement with the experiment, with an error of less than 6%. In the numerical simulation, the lattice size of the three TPMS is 20 × 20 × 20 mm3, the fluid is air, the heating surface is heated at a constant wall temperature of 373.15 K, and the Reynolds number is in the range of 166–940. Compared with the Fins-structure model, the Nusselt number of TPMS-Diamond is increased by 9–196%, that of TPMS-Gyroid is increased by 5.8–149%, while the TPMS-Iwp is increased by 6.8–43.5%. Among the three TPMS structures, the convective heat transfer performance of TPMS-Dimond is the best, which can be attributed to its geometric structures without the “through-holes,” which leads to a more substantial disturbance of the wall to the fluid, thereby enhancing the heat transfer.

Improvement of heat sink performance using paraffin/graphite/hydrogel phase change composite coating

Phase-change materials offer high latent heat and are widely used for energy storage applications. Paraffin wax is usually used as a phase-change material. However, its application in energy storage is restricted due to its low thermal conductivity. In the present work, graphite and graphite-hydrogel are used to enhance the thermal conductivity and heat release properties of paraffin wax. Wax-graphite (W-G) and wax-graphite-hydrogel (W-G-H) composites were synthesized by the dispersion of graphite and graphite-hydrogel in paraffin wax above its melting temperature. Scanning electron microscope (SEM) analysis was used to investigate the graphite and graphite-hydrogel distribution in the paraffin wax matrix. Thermogravimetric analysis (TGA) and differential scanning calorimeter (DSC) characterization were performed to measure the thermal stability and phase transition properties, respectively. DSC revealed that all composites have a similar melting temperature. The W-G-H composite displayed nearly 12 folds more thermal conductivity compared to the pure paraffin wax. High temperature brings adverse impacts on energy efficiency, and even destroys a semiconductor device. The synthesized W-G-H composite is proposed to decrease the working temperature of semiconductor devices. As an applicative demonstration, the W-G-H composite film was coated at the back of the solar panel. The W-G-H composite coated solar panel displayed a surface temperature that was near ∼4 °C lower than the bare solar panel while operating. The real-time experiment indicates that the W-G-H composite has high thermal conductivity and heat release properties. The study reports fundamentally new low-cost, simple, scalable, and self-adaptive, passive cooling technology to the semiconductor industry. The proposed material can further be developed in the form of paint and its heat sink properties can be improved by introducing hydrogels doped with Li+ and Br− ions.

Bio‐Sourced Intumescent Nanocoating

Nylon–cotton blended fabric (NYCO), commonly used in military uniforms and workwear for its comfort and resilience, presents an inherent fire risk due to its high flammability and high heat release. There are few effective flame retardant treatments for NYCO that are environmentally benign and maintain the hand of the fabric. To solve this problem, a layer‐by‐layer (LbL)‐assembled 15 quadlayer (QL) coating, consisting of chitosan (CH), phytic acid (PA), and tannic acid (TA), is applied to NYCO. Individually pairing TA or PA with CH is not self‐extinguishing, but they work synergistically in the QL system to create an effective intumescent coating. This completely bio‐sourced, water‐based coating self‐extinguishes in a vertical flame test (ASTM D6413), with only 16.6% weight added to NYCO, yielding 91% postburn residue and a 51% decrease in peak heat release rate. This novel coating provides an opportunity to replace environmentally questionable flame retardant treatments with a fully sustainable system.

A “riding” combustion mode in CuO/Al reactive multilayer nano-foils

Reactive multilayer nano-foils possess high heat release and combustion temperature, which makes them very attractive for advanced applications, such as materials joining materials, tuning ignition and actuation, energy microsources, and others. The combustion mechanism of CuO/Al foils has not been adequately described yet. In this work, we report experimental evidence of an amazing combustion mode in CuO/Al reactive multilayer nano-foils. A set of droplets of molten combustion products forms behind the reaction front and “rides” this front under the action of surface tension. When the combustion front arrives at the edge of substrate and stops, the droplets start to fly-by inertia along-track direction of the combustion propagation. Thus, the combustion front can throw hot micro-droplets toward a predetermined target to perform some specific action, e.g., distance ignition, actuating pulse, or energy transfer.

Optical diagnostics of methanol active-thermal atmosphere combustion in compression ignition engine

Methanol has become one of the research hotspots of internal combustion engine in recent years. One method of methanol compression ignition is that create in-cylinder active-thermal atmosphere to ignite direct injection (DI) of methanol. However, the combustion essences and related mechanisms in methanol active-thermal atmosphere combustion (ATAC) have not been comprehended. In current study, the characteristics of methanol ATAC were investigated on a light-duty engine using different optical diagnostics. Polyoxymethylene dimethyl ethers (PODE2) and n-heptane were chosen as port injection (PI) fuel respectively, and methanol was used as DI fuel. The experiment results indicate that methanol ATAC with PI of PODE2 is divided into two combustion processes. One process is the premixed combustion of PODE2 and the partially premixed combustion (PPC) of methanol, which appears that the premixed blue flames of PODE2 and the partially premixed yellow flames of methanol. The other is PODE2 premixed combustion and methanol diffusion combustion, which presents that the premixed blue flames of PODE2 and the yellow spray diffusion flames of methanol. Both the heat release rate and the flame structure of methanol ATAC can be adjusted by changing DI timing. The increase of PI energy proportion advances the timing of premixed blue flames of PODE2. The DI of methanol is driven by spray diffusion flames unless the methanol injection timing is earlier than high temperature heat release of PODE2. The capability of PODE2 to make methanol auto-ignited is higher than that of n-heptane. The methanol energy proportion can achieve 70% in PODE2 case, while achieve merely 30% in n-heptane case. Kinetic analysis reveals that the ignition delay times of PODE2 are lower than that of n-heptane even at lower equivalence ratio. The KL factor of methanol diffusion flame ranges from 0.02 to 0.04, which is remarkable lower than diesel spray flames. The methanol ATAC achieves higher substitution rate of methanol and the flexible combustion process can be obtained using PODE2 as PI fuel.

Effect of azide polyether pyrolysis property on combustion and heat release of boron-based fuel-rich propellant

Overcoming the severe particle agglomeration of unreacted fuel boron (B) in combustion process to enhance the heat release efficiency of B-based fuel-rich propellants is still a great challenge. Glycidyl azide polyether (GAP) was introduced to synthesize GAP-based energetic thermoplastic elastomer (GAP-ETPE) binder, which was used to fabricate the B/GAP-ETPE propellant. High GAP content (85 wt%) can be used to synthesize 85%GAP-ETPE as the binder. With the increase of GAP content, the decomposition conversion rate of GAP-ETPE was increased and the apparent activation energy (Ea) of B/GAP-ETPE propellant was decreased. The heat of explosion and combustion of B/85%GAP-ETPE were increased from 4004.1 kJ/kg to 4546.2 kJ/kg and 24,056.5 kJ/kg to 24,938.3 kJ/kg, respectively. The combustion results showed that the burning rate of B/85%GAP-ETPE (3.1 mm/s) was higher than that of B/TPE (1.8 mm/s) using a thermoplastic elastomer (TPE) without GAP, and the particle injection effect was significantly improved. The pressurization rate of B/85%GAP-ETPE (85 wt% is maximal GAP content in binder in current study) was 2.6 MPa/s during combustion in a closed bomb, which was higher than that of other prepared B/GAP-ETPE, showing the propellant using GAP-ETPE with high GAP content exhibited better gas formation and higher heat release, which provided good dispersion and less particle agglomeration of B particles when burning. This strategy enables B to be ejected more effectively in the combustion process to achieve a better combustion performance and heat release.

Large eddy simulation of transient combustion and soot recession in the ECN Spray A and D flames

This paper presents the numerical results of combustion and soot recession in the Engine Combustion Network (ECN) Spray A and D flames using large eddy simulations (LES). The nominal injector nozzle diameters for the ECN Spray A and D are 90μm and 186μm. A two-equation soot model is implemented to model the soot formation and oxidation processes. The numerical model is validated by comparing the simulated and measured data in terms of ignition delay time (IDT), lift-off-length (LOL), and temporal evolution of soot mass. The combustion and soot recession processes are analyzed after the end-of-injection (AEOI). The combustion recession processes are first driven by auto-ignition wave propagation followed also by the convective flow in both the Spray A and D flames. A separated high-temperature flame structure is observed in the Spray A flame due to having small favorable mixture regions for the auto-ignition to occur upstream of the quasi-steady lift-off position AEOI. In contrast, a spatially-continuous high-temperature flame structure is formed in the Spray D flame due to having more ignitable mixture regions upstream of the quasi-steady lift-off position and a higher heat release. Soot recession is observed in the Spray D flame but not in the Spray A flame. This is attributed to the mixture upstream of the quasi-steady state soot region becoming favorable to promote soot formation in the Spray D flame, but it becomes fuel-lean AEOI in the Spray A flame.

Optical diagnostics of misfire in partially premixed combustion under low load conditions

To clarify the misfire mechanism is important for stabilizing combustion in partially premixed combustion (PPC) under low load. Fuel-tracer planar laser-induced fluorescence (PLIF), formaldehyde PLIF, flame and OH* natural luminosity imaging were utilized to qualify the local equivalence ratio, low-temperature reaction and the high-temperature flame features in an optical engine. Results show that in high direct injection (DI) pressure (1000 bar), due to excessive premixing, the local equivalence ratio in the initial timing of the high temperature heat release (HTHR) is low. Although the auto-ignition flame kernels are formed in high DI pressure, they cannot stably develop, resulting in misfire during the flame development process. In late DI timing (-5 crank angle degree after top dead center, °CA ADTC), since the whole heat release process occurs in the expansion stroke, the in-cylinder temperature and pressure continue decreasing. Although the local equivalence ratio in some regions is high enough, the in-cylinder thermodynamic environment does not support the generation of more auto-ignition flame kernels, thus a small amount of auto-ignition flame kernels can only develop through flame propagation. In short, the misfire of PPC occurs in regions where the equivalence ratio is low or the in-cylinder thermodynamic environment does not further support flame development. Therefore, the trade-off relationship between equivalence ratio and temperature determines the formation of auto-ignition kernels. The local equivalence ratio and temperature distribution near the initial timing of HTHR is the key factor to ensure the subsequent stable combustion. Taking the ambient pressure of 18 bar as an example, the boundary condition where the autoignition kernels are most likely formed or the charge is most likely ignited by the nearby flame kernels is in the range of 0.53–0.62 for equivalence ratio and 740–757 K for temperature. The misfire region most likely appears when the equivalence ratio is lower than 0.49. It can be concluded that the misfire of PPC results from the synergistic effect of local equivalent ratio and temperature. The controlling parameters of injection pressure and injection timing are actually optimizing the suitable combinations of equivalence ratio and temperature to stabilize combustion.

Preparation and Performance Enhancements of Low-Heat-Releasing Polyurethane Grouting Materials with Epoxy Resin and Water Glass

Polyurethane (PU) grouting materials possess excellent fluidity and strong injectability. However, the high heat release during the reaction process restricts its application. In this study, with the addition of water glass (WG), a prepolymer was prepared by epoxy resin reacted with isocyanate to form modified polyurethane. The effects of epoxy resin and water glass on the compressive properties, expansion rate, structure of the cell, and maximum reaction temperature of the grouting materials were also investigated. The results showed that the cell size of modified PU was smaller and more regular, the maximum reaction temperature of the modified PU was reduced to 89 °C, and the compressive strength and expansion rate went up to 0.27 MPa and 57, respectively. This investigation will expand the application of PU grouting materials in underground engineering.

Experimental investigation into the effects of pilot fuel and intake condition on combustion and emission characteristics of RCCI engine

Due to the excellent physicochemical properties, coal to liquid (CTL) is suitable for use as an alternative fuel in internal combustion engines. It is conducive to promoting efficient and clean utilization of coal. In this study, the experiment of using CTL and conventional diesel as pilot fuel and gasoline as the premixed fuel was carried out on a modified dual-fuel engine. The combustion boundary conditions, including gasoline ratio, intake flow rate, and intake temperature, were modulated at an engine speed of 1400 rpm and under low load. The combustion parameters and emission characteristics were fully discussed. The results show that both gasoline/CTL reactivity controlled compression ignition (RCCI) mode and gasoline/diesel RCCI mode contain low temperature heat release (LTHR) and high temperature heat release (HTHR) phases. Among them, the gasoline/CTL RCCI mode has a higher proportion of LTHR, and the low-temperature combustion occurs later than gasoline/diesel. Besides, the ignition delay (ID) of gasoline/CTL RCCI mode is generally shorter, and CA50 is more forward than that of gasoline/diesel RCCI. Compared with gasoline/diesel RCCI mode, the intake air flow has a more significant effect on the indicated thermal efficiency (ITE) and particle emissions of gasoline/CTL RCCI. In particular, the problem of high accumulation mode particles brought by the CTL can be solved by appropriately increasing the intake flow rate. There is an optimal intake temperature for the ITE of gasoline/CTL RCCI mode, while the ITE of gasoline/CTL RCCI mode remains almost constant as the intake temperature increases. Compared with diesel, when using high cetane number (CN) CTL as a pilot fuel, the combustion is more stable, and the ITE of that at each operating condition is about 3% higher. Under optimum intake conditions, the gasoline/CTL RCCI mode achieves higher thermal efficiency and products lower CO, HC, and particle emissions, but NOx emissions increase slightly.

Numerical investigation on movement of triple points on oblique detonation surfaces

A normal detonation wave in a gaseous mixture is a transient, multidimensional structure containing triple points (TPs) that collide in pairs and then propagate oppositely. However, the TPs on an oblique detonation wave (ODW) almost propagate along the same direction in most studies. In this study, the reactive Euler equations coupled with a two-step induction–reaction kinetic model are used to solve a two-dimensional wedge-induced ODW. Two novel movement patterns are observed in most cases. Results show that the TPs of the ODW can propagate upstream and even stand on the wave surface. The movement patterns of TPs include downstream, upstream, and steady according to their propagation direction relative to the wedge. We find that the ratio of the post-ODW flow speed Uτ to the transverse wave speed UT dominates the TP movement types. When the speed ratio Uτ/UT is approximately equal to 1, the TPs can stand on the wave surface. Above unity, downstream TPs form, and upstream TPs correspond to a value smaller than 1. Furthermore, the inflow Mach number has little influence on UT, while Uτ changes significantly. This is largely due to the high sensitivity of the ODW angle to the inflow. The high heat release rate benefits upstream TPs, and steady TPs form under a large wedge angle. The results are confirmed by varying the inflow Mach number, wedge angle, and chemical parameters.

Experimental study on the effects of injection timing and n-butanol energy ratio on combustion and emissions of n-butanol/diesel DFDI engine

In this paper, a dual-fuel direct injection (DFDI) system was designed by utilizing two common-rail direct-injection systems in a modified single-cylinder engine. Diesel and n-butanol were directly injected to realize the stratifications of fuel-air mixtures and reactivity. The effects of the n-butanol energy ratio (BER) and fuel injection timing on engine combustion and emission characteristics were studied under low and medium load. The combustion phase was retarded, indicated thermal efficiency (ITE) decreased and COV of IMEP increased as increasing BER under each load. Under low load, the n-butanol injection timing was suggested near 125° CA BTDC to increase ITE, by modifying the stratification of the n-butanol at a favorable level. With an advance of diesel injection timing, the combustion phase was advanced at first and then retarded; ITE was also increased firstly and then decreased. Under medium load, the two-stage high temperature heat release event could be observed. Early n-butanol injection condition was preferred to achieve higher ITE and lower COV of IMEP. The early diesel injection operation was suggested under medium load for increased ITE, together with the decreased nitrogen oxide and soot emissions. In general, compared with pure diesel operation, stable and high-efficient combustion could be achieved in n-butanol/diesel DFDI mode, while the ITE could increase 2.8%; NOx and Soot emission decreased 82% and 79%.

Fire Properties of Bed Mattresses Focusing on the Fire Growth Rate and Flame Height.

Bed mattresses are rated as products to cause a fire hazard because of their very high heat release rate among indoor combustibles. In this study, fire growth rate and flame height were measured through a series of combustion experiments on a full scale in order to provide information regarding mattress fire characteristics. The experiments were conducted in an open space, and bed mattresses as the test samples were installed at different installation heights (0~515 mm). The experiment results revealed that the higher the bed mattress was installed, the higher the fire growth rate, the heat release rate, and the flame height. Additionally, the time of the mattress to reach 1 MW was evaluated as the category “medium” in the NFPA 72 standards. The flame heights showed a good coincidence compared to the existing flame height model equations, proving the applicability of the model to the mattress combustion.

Performance, emission and combustion characteristics of a diesel engine fuelled with diesel/coconut shell oil blends

In this work the coconut shell oil (CSO) - diesel blends are utilized in a compression ignition (CI) engine and its performance, combustion and emission behaviour are analysed with different loading conditions. The coconut shell oil is extracted from coconut shells by the pyrolysis method conducted in an oxygen-free environment with different processing temperatures. The extracted fuel was tested in a single-cylinder, four-stroke, direct-injected (DI) diesel engine with different diesel/coconut shell oil blends (CSO20, CSO40, CSO60, CPO80 and CSO100). During the experimentation, the engine was operated with a constant speed of 1500 rpm and an injection pressure of 250 bar at 23 deg before TDC. The result of this study is clearly showing that the neat coconut shell oil and its blends could be used effectively in diesel engines with better thermal efficiency and exhaust pollutants. It is found that the total fuel consumption by the diesel engine is increased with the presence of CSO in the blends. The blend of CSO20 has registered a lower fuel consumption rate compared to other blends, due to its high heating value. The brake thermal efficiency (BTE) of diesel engines operated with CSO and its blends have registered lower values compared to diesel fuel. The blend of CSO20 has resulted with high heat release rate (HRR) and in-cylinder pressure compared to other blends. The exhaust pollutants like carbon monoxide, hydrocarbon and smoke from CSO blends were registered at different values based on the presence of CSO in the blends. The blend of CSO20 has produced lower pollutants compared to other blends, which is nearer to the values of diesel fuel. The blends of CSO80, and CSO100 produced lower NOx emissions compared to neat diesel and other blends.

Comparative Analysis of Heat Release, Bound Water Content and Compressive Strength of Alkali-Activated Slag-Fly Ash

Optimizing the mix composition of alkali-activated materials is sometimes overwhelming due to the higher number of potential parameters that could be varied compared to designing a mix based on Portland cement. The present work focuses on understanding the correlations between compressive strength, bound water content, and heat release from the calorimeter. Different slag and fly ash proportions are studied at two different solution-to-binder (S/B) ratios. Alkali solutions are made with 5 M NaOH and water glass to have a final silica modulus of 1.28. Results indicate that, at similar S/B ratios, mixes with high amounts of slag develop high compressive strength corresponding to high bound water contents until 28 days and high heat release until 7 days. A good correlation exists between compressive strength with cumulative heat release and bound water content when the water-to-solid ratio of the initial mixture is also considered. These findings promise a less tedious method that could be employed to optimize the process for the mix design of alkali-activated materials.

An experimental study on biodiesel production and impact of EGR in a CRDI diesel engine propelled with leather industry waste fat biodiesel

The purpose of the predominant endeavor is the way of through an experiment aspect for the reticular effect of exhaust gas recirculation (EGR) on combustion, performance, emissions besides energy characteristic of common rail direct injection (CRDI) engine fuelled with leather industry waste fat biodiesel and diesel blends. Biodiesel was converted by the transesterification process from the raw fat oil extracted with leather waste fat feedstock. This work takes advantage of blends of both like B10, B20, B30 along with engines that were run with various EGR rates (5%, 10%, and 15%) to evaluate engine outcome parameters. The maximum in-cylinder pressure was examined with the blend B20 with EGR 5% rate about 6.65% higher than pure diesel fuel. The high heat release rate (HRR) was ascertained with the blend B30 with EGR 10% rate about 23.81% higher than neat diesel fuel. The brake thermal efficiency (BTE) for the blend B10 with EGR 5% rate is higher than other test conditions but 4.2% let down associated with simple diesel fuel. The nitrogen oxides (NOx) were lesser than the clean diesel fuel at all test fuels, the highest NOx emission reduction was achieved in blend B30 with EGR 15% rate of about 87.59% than neat diesel fuel operation. The smoke opacity increased by raising the EGR level, the combination B30 with EGR 5% rate displayed low smoke opacity about 64.5% lower than neat diesel fuel. The hydrocarbon (HC) emission was lower than neat diesel at a low EGR rate, the blend B10 with EGR 5% rate displayed the lowest HC emission about 85.71% decreased then neat diesel operation. The carbon monoxide (CO) emission displayed lower than neat diesel at low EGR rate, the blend B10 with EGR 5% rate displayed the lowest CO emission about 50% than neat diesel. As of energy analysis, it was noted that the heat equivalent to brake power and heat lost to engine cooling water is higher in diesel fuel than biodiesel blends and the heat lost to exhaust gases and heat unaccounted loss were lower in diesel than biodiesel blend. Finally, the TOPSIS optimization study was carried out for finding the optimum input conditions which could result in improved combustion, performance, and reduced emissions. The B30% blend with EGR 15% at full load achieved 1st rank with 0.849 relative closeness value. So, this operating condition was projected as the best prospect for the application of a CRDI diesel engine.

Multi-objective optimization of performance and emission characteristics of a CRDI diesel engine fueled with sapota methyl ester/diesel blends

This study examines the combined effect of compression ratio (CR) and exhaust gas recirculation (EGR) on combustion, performance, and emissions characteristic of a common rail direct injection (CRDI) engine fueled by sapota methyl ester (SME) and diesel blend. Biodiesel extracted from sapota fruits waste seeds through the transesterification process. This work utilised diesel-biodiesel blend B50% blend (D50SME50 by vol.), and the engine was run with different compression ratios (16, 17.5, and 19) and EGR rates (0%, 10%, and 20%) to evaluate engine outcome parameters. The result found that the ignition delay was reduced with an increased compression ratio. The high heat release rate (HRR) was ascertained with the CR 16 and EGR 10% rate, about 6.01% higher than diesel fuel. The highest in-cylinder pressure was observed with the CR 19 and EGR 0% rate, about 2.02% higher than diesel. The thermal brake efficiency (BTE) for CR 16 and EGR, 0% rate, is higher than other test conditions but 11.21% lower than neat diesel. The nitrogen (NOx) emission oxides for all the test conditions were lower than neat diesel. The highest NOx emission reduction was achieved in CR 16, and EGR 20% rate about 61.91% lower than diesel operation. The smoke opacity increased by increasing the EGR rate. The CR 17.5 and EGR 0% rate displayed lower smoke opacity, about 2.5% lower than diesel operation. The hydrocarbon (HC) emission was lower than neat diesel at all operating parameters. The CR 17.5 and EGR, 0% rate, displayed the lowest HC emission, about 44.82% decreased than neat diesel operation. The carbon monoxide (CO) emission displayed lower for the EGR 0% rate at all the compression ratios. The CR 16 and EGR 0% rate displayed the lowest HC emission, about 10.77%, than diesel operation. The energy analysis noted that the fuel energy input and energy for brake power and energy flown through the exhaust gases are higher in diesel fuel than biodiesel blend. The unaccounted losses were low in diesel than biodiesel blend. Finally, the TOPSIS optimization study was carried out to find the optimum input conditions to improve combustion, performance, energy, and reduced emissions. The B50% blend with CR 16 and EGR 20% at full load achieved 1st rank with 0.809 relative closeness value. So, this operating condition was projected as the best prospect for applying in a CRDI diesel engine.