Reduce Heat Loss Research Articles

On the flow-facilitated ignition in a mixture with low Lewis number

The imposed laminar flow has been shown to facilitate ignition under certain conditions in our previous work (Chen et al. 2023). Such flow-facilitated ignition (FFI) was observed only for mixtures with sufficiently large effective Lewis numbers, i.e., Le>>1. It is not clear whether FFI can also occur in a mixture with Le<1 and Le∼1. This study will investigate the occurrence of FFI in a mixture with low Lewis number. We conduct multi-dimensional simulations of forced ignition by a pair of electrodes in both static and flowing hydrogen/air mixtures. A simplified ignition model is used in simulations. The laminar flow direction is perpendicular to the pair of electrodes. We consider different values for equivalence ratio (ϕ=0.4 and 1.0), pressure (P = 0.3–1 atm), electrode gap distance (dgap=0.64–3.88 mm) and flow velocity (Uin=0–10 m/s). The simulation results show that FFI can occur in a fuel-lean (ϕ=0.4) H2/air mixture with Le≈0.43 at sub-atmospheric pressure. This indicates that large Lewis number is not a necessary condition for FFI occurring in simulations considering a simplified ignition model. Here, the favorable conditions for FFI are large critical ignition radius at sub-atmospheric pressure, sufficiently small electrode gap distance and moderate flow velocity. Moreover, the reduction in heat loss to the electrodes by the imposed flow is found to be crucial for FFI. To further understand the boundary conditions of FFI, an ignition mode regime diagram in terms of flow velocity and normalized critical ignition radius (i.e. the ratio of critical ignition radius and electrode gap distance) is proposed. The present study provides insights on the effects of laminar flow on forced ignition of premixed flames.

REDUCED HEAT LOSS THROUGH WINDOW STRUCTURES

The results of theoretical and experimental studies of heat transfer through the window structures of the building are presented, the thermal characteristics of the windows are established and the level of heat loss realized through them is estimated. To determine the heat transfer resistance of two-chamber double-glazed units, numerical modeling of radiative-convective heat transfer is performed, taking into account the thermal conductivity of the gas layer between the glasses. Natural free convection of the gaseous medium in the double-glazed chambers occurs as a result of the temperature difference between the side glass surfaces of the chamber. Modeling is performed by numerically solving the system of fluid dynamics and energy equations for the air layer and glass. On the inner surfaces of the chambers, conditions of the fourth kind are set, which take into account the radiation and conductive components of the total heat flow coming from the glass surface. The results of simulation of heat transfer through double-glazed windows with ordinary glass indicate that about 60 % of heat is transferred by radiation. Therefore, an effective measure to reduce heat loss through windows is to reduce the radiation component of the total heat flow by applying a low-emissivity coating to the inner surfaces of the glass unit. This makes it possible to reduce the total heat flow (and, accordingly, heat loss to the environment) by 20–34 %, depending on the number of glass surfaces with this coating. Conducted independent experimental studies confirm the modeling results. In order to comply with the current requirements of state building regulations and to achieve the energy efficiency class of type C buildings (specific heat consumption for heating 1 sq. m of usable area is less than 75 kWh), for the climatic conditions of Kyiv, it is recommended to use double-chamber windows with two low-emission coatings with the formula of the glass unit: 4M1-10-i4M1-10-i4M1. Bibl. 22, Fig. 8.

Numerical investigation of thermomechanical behavior of Yttrium barium zirconate-coated aluminum alloy piston in an internal combustion engine

Increasing engine power to volume density is under investigation and being analysed extensively. Turbocharger, which is used to boost volumetric efficiency, also raises cylinder temperature and pressure, thus resulting in thermal distortions and reducing clearances in tribo-contacts, thereby compromising engine life. Thermal barrier coatings (TBCs) have shown potential to provide remedies to reduce heat losses, hazardous emissions, and heat flow toward the piston skirt in an internal combustion engine. In this study, a detailed thermo-mechanical analysis was performed for a diesel engine piston with a novel yttrium barium zirconate (YBZ) coating and then compared with other TBCs with varying thicknesses. The results revealed a notable decrease in piston substrate surface temperature when coated with various TBCs, with YBZ coating demonstrating superior performance over others. The 0.2 mm coating of YBZ-coated piston exhibited significant reductions of 15% and 10.3% in temperature and thermal stress respectively, thus enhancing piston durability. The better performance of the novel YBZ coating could be attributed to its stable thermal and elastic properties and lower thermal conductivity than other TBC materials. YBZ coating provides a promising solution to improve engine efficiency while extending engine life, making it an attractive option for the automotive industry.

Comparative assessment of high efficiency flat solar thermal collectors’ performances

The study investigates the performances of high efficiency flat solar thermal collectors, under the climatic conditions of Galați, Romania. The same mathematical model was used to evaluate the stationary and the transitory thermal behavior of 12 high effic iency collectors, with reduced heat losses. The thermal characteristics of the collectors were extracted from the technical reports of two European independent testing laboratories. The annual specific energy production was found to vary in a large domain between 415.9 kWh/m2 and 947.9 kWh/m2, the maxim value representing more than the double of the minimum one. It was highlighted that both the optical efficiency and the heat losses contribute to the global efficiency of the flat solar thermal collectors, and the most efficient one is the flat evacuated one.

A review on methods of water softening processes for improving efficiency of bio-mass fired boiler

In order to create the steam needed for the industrial process specifically for a laundry process, bio-mass fired boilers are employed. A biomass fired boiler's production rate and efficiency is directly influenced by its effectiveness and safety. Therefore, for the industry to maintain continuous output, biomass fired boiler functioning must be at its best and efficient. The main issues that can result in reduction of efficiency and output in the bio-mass fired bioler is due to boiler tube corrosion and scale formation. The quality of the untreated water which is hardened in nature is one of the primary causes of scale formation. Therefore, to optimize the boiler function, improvement in water quality can help in preventing corrosion and the development of scale. There are various processes for treating water commonly called as water softening done by either by mixing /adding chemical agents in the water itself or by treating water from exterior. However the cost and quality of the softening technology is important for the industry. The cost of operating the boiler can be decreased by using an alternate fuel, reducing heat losses and elimination of scale formation in the boiler. This article is specifically confers about increase in efficiency of boiler by the elimination of scaling in the boiler. Various relevant research papers are studied on technologies for water treatment with advantages / disadvantages and cost effectiveness. This article focuses to review research papers which were written for the improvement of feed water to biomass fired boiler by studying various water softening techniques and suggest optimized solution to the company.

Improvement of the method of calculation of the reduced heat transfer resistance of light openings of buildings

During the construction of buildings in regions with relatively low outdoor temperatures it is necessary to pay more attention to the issues of heat preservation and minimizing heat losses through external enclosing structures. The paper analyzes the main ways of heat loss minimization through translucent enclosing structures. It is revealed that it is more expedient to reduce heat loss through a window structure by using an effective double-glazed window. The main methods of increasing the reduced resistance to heat transfer of a double-glazed window are described. The methods of reducing heat transfer which occurs due to convection and radiation are analyzed. The reasons for the need for the use of energy-efficient double-glazed windows are given.

Enhancing Energy Efficiency of Cold‐formed Steel Framed Walls with Vacuum Insulation Panels

AbstractIn the current evolving building construction sector, the use of cold‐formed steel frames (CSF) has gained popularity due to their fast, clean, and flexible constructability. On the other side, in terms of the energy efficiency of a building, the use of CSF has raised concerns due to their high thermal conductivity, especially in the case of external wall panels. Hence, it is crucial to examine the thermal performance of such wall configurations and find solutions to reduce heat loss through walls by lowering the thermal transmittance, which would ultimately enhance the energy efficiency of the buildings. Accordingly, this study focuses on analysing the thermal performance of external wall panels made of cold‐formed and thin‐walled steel‐lipped channel studs with plasterboard linings and vacuum insulation panels (VIP). 2D and 3D finite element models developed in ABAQUS were used to analyse the effect of using VIP, oriented strand board and plasterboard, and their positions on the thermal transmittance of the CSF walls. 70 numerical analyses were conducted on 35 wall configurations and the results obtained were checked against the U‐value requirements set by UK building standards. It was found that replacing oriented strand boards with plasterboards does not substantially affect the thermal transmittance of the wall. However, adopting VIP as an insulation material has shown a U‐value reduction of up to 77%. But again, the change in position of VIP in the wall cross section has no notable effect on the U‐value.

Grain Structure Evolution in 6013 Aluminum Alloy during High Heat-Input Friction-Stir Welding.

This work was undertaken to evaluate the influence of friction-stir welding (FSW) under a high-heat input condition on microstructural evolution. Given the extreme combination of deformation conditions associated with such an FSW regime (including the highest strain, temperature, and strain rate), it was expected to result in an unusual structural response. For this investigation, a commercial 6013 aluminum alloy was used as a program material, and FSW was conducted at a relatively high spindle rate of 1100 rpm and an extremely low feed rate of 13 mm/min; moreover, a Ti-6Al-4V backing plate was employed to reduce heat loss during welding. It was found that the high-heat-input FSW resulted in the formation of a pronounced fine-grained layer at the upper weld surface. This observation was attributed to the stirring action exerted by the shoulder of the FSW tool. Another important issue was the retardation of continuous recrystallization. This interesting phenomenon was explained in terms of a competition between recrystallization and recovery at high temperatures. Specifically, the activation of recovery should reduce dislocation density and thus retard the development of deformation-induced boundaries.

An Examination of Heat Transfer Dynamics in Pulsating Air Flow within Pipes: Implications for Automotive Exhaust Engines

The detailed understanding of heat transfer in the pulsating airflow in the pipe is critical to reducing heat losses in the engine exhaust stream and improving catalyst performance. In the present investigation, we have scrutinized the impact of pulsation frequencies ranging from 0-90 Hz on the flow velocity field and the consequent heat transfer through a horizontal pipe wall. The Nusselt numbers were evaluated at three distinct cross-sectional points moving from upstream to downstream, by systematically modulating the frequency. Temporal variations in the velocity field and temperature were captured utilizing particle image velocimetry (PIV) and dual-thermocouple probes, respectively. Intriguingly, while the Nusselt number for steady flow at 0 Hz closely adhered to Gnielinski’s equation, the pulsating flow demonstrated a peak between 25-35 Hz, a pattern not predicted by the prevailing quasi-steady-state theory. The observed frequency response of turbulence was found to be congruous with the Nusselt number, indicating that the heightened heat transfer at frequencies of 25-35 Hz could be attributed to the enhanced turbulence and the temperature gradient between the fluid and the wall surface during the deceleration phase in the hysteresis of turbulence in the pulsating flow. The unique frequency characteristics of heat transfer that were uncovered in this study, with respect to both flow velocity and temperature, offer valuable insights for devising strategies to mitigate heat loss during ignition and idling. Furthermore, these findings provide robust benchmarks for validating numerical simulations of pulsating flows in real-life automotive engines.

A Simple, Mild, and Low‐Cost Method for Preparation of Wood‐Nigrosine in Solar‐Driven Interfacial Evaporation System

The solar‐driven interfacial evaporation system has attracted much attention in recent years due to its reduced heat loss and accelerated steam generation. As a low‐cost and readily available resource, wood is widely applied as photothermal materials in solar‐driven interfacial evaporation system because of its superior water transfer and heat loss prevention properties. Herein, a simple, mild, and cost‐effective method is employed to fabricate wood‐based photothermal materials. The results demonstrate that the solar absorption rate of wood‐nigrosine is more than 97.5% across a wide wavelength range (200–2500 nm), and an evaporation rate of 1.46 kg m−2 h−1 and evaporation efficiency (86.1%) are achieved under 1‐sun illumination (100 mW cm−2). The solar‐driven interfacial evaporation system based on wood‐nigrosine exhibits strong structural stability and processing capability for dyes and seawater.

Effect of ring groove in a heat-insulating insert on efficiency of its work in blast channel of blast furnace tuyere

One of the main disadvantages when supplying natural gas to the air tuyere of a blast furnace is low intensity of its combustion inside the tuyere blast channel. Ring groove on the surface of blast channel improves the mixing of natural gas with blast and increases completeness of gas combustion in it, but reduces the tuyere durability. One of the ways to simultaneously solve these problems is to install a heat-insulating ceramic insert in the tuyere blast channel. The insert significantly reduces heat losses through the tuyere surface, improves natural gas combustion in the blast channel due to its contact with hot walls of the insert instead of cold copper walls in its absence. This increases the temperature of the hot blast at the tuyere outlet. In addition, the insert affects the tuyere durability by reducing the heat flow acting on the tuyere. In this work, we studied influence of the ring groove and its parts in the insert on efficiency of its work. In the Ansys 21.1 software, the processes occurring in the blast channel of a blast furnace tuyere with a ceramic insert installed in it, having a groove of a quadrangular section in the form of a ring or its part in the circumferential direction, were simulated. It was established that improvement of natural gas combustion in the tuyere blast channel is achieved using a ring groove or part of it from the side of gas supply.

Evacuated tubes solar air collectors: A review on design configurations, simulation works and applications

One of the primary components of solar energy utilization systems is evacuated tube solar air collectors (ETSACs). The irradiance is absorbed by these collectors, which is then transformed into thermal energy at the absorbing surface before being transmitted to the air passing through the collectors. This type of collector outperforms flat plate collectors in terms of reducing heat loss through conduction and convection and also during cloudy days; thus, ETSACs are the most preferred collectors to be applied for space heating, crop drying, and industrial applications. This review focuses on a summary of design configurations, simulation works, and applications of ETSACs in order to understand the influence of the thermal performance of ETSACs so that these collectors can be applied more effectively. Studies on the use of nanofluids as thermal performance enhancers and phase change materials as thermal storage media can be considered to enhance the thermal performance of ETSACs.

Reducing the Harmful Impact of Boiler Plants on the Environment

World production makes an ever-increasing harmful impact on the natural environment. As a matter of fact, mankind is facing the problem of saving the natural environment. As for the production branches the energy industry has the strongest harmful effect, and as for the production facilities the boiler plants that emit heat and harmful substances into the environment are the most environmentally aggressive. The global fleet of boiler plants is huge and complicated. As the boiler plant wears out, the levels of its environmental, economic and general technical efficiency are increasingly decreased, and the intensity of the harmful impact on the environment is increased worsening progressively its condition. The self-healing process of the natural environment lags behind the process of harmful effects on it. As a matter of fact, the problem of reducing the harmful effects of boiler plants on the environment has arisen. The purpose of this study was to analyze the phenomenon of interaction between the energy sector, primarily boiler plants and the natural environment and search for the ways to resolve the existing contradictions of this interaction. The task of improving the environmental friendliness of worn-out power equipment and, above all, boiler plants is an urgent issue. The purpose of this research paper was to analyze the possibilities of solving the problem of ecological interaction of boiler plants with the natural environment through their partial, full or redundant renovations. This research is relevant, because the boiler plants of the domestic fleet are extremely worn out. Full or redundant renovation is highly resource intensive and appropriate resources are currently unavailable. A realistic way to solve the problem of reducing the harmful effects of boiler plants on the environment is to increase the environmental friendliness of worn-out boiler equipment by partially upgrading it using relatively simple and affordable methods, such as normalizing the boiler air mode, reducing heat losses with exhaust gases, rationalizing and implementing daily and weekly schedules of the boiler operation in order to extend the full load carrying mode. Successful implementation of the forthcoming program of partial renovation of worn-out boiler plants will ensure a significant reduction of their harmful impact on the environment.

Inferring the lifestyles of extinct Crocodyliformes using osteoderm ornamentation.

Osteoderms are bony plates formed within the dermis of diverse vertebrate groups. They are present in all crocodylomorphs but Metriorhynchidae. Most of them show typical bone ornamentation consisting of pits and ridges on their outer surface. The most widely discussed functional hypothesis suggests that the ornamentation of osteoderms influences heat exchange with the environment through the adjacent vascular network, facilitating the absorption of solar radiation. This process allows semiaquatic crocodiles to compensate for heat loss resulting from the high thermal conductivity of surrounding water. In order to test this assertion, we conducted a phylogenetic logistic regression analysis to evaluate the relationship between osteoderm relative area of pits (RAP) and lifestyle (terrestrial versus aquatic) in a sample of crocodyliforms. Our results revealed that lifestyle is significantly explained by RAP: the lower the degree of ornamentation (RAP), the higher the probability of a terrestrial lifestyle. We used this model to infer the lifestyle of two extinct taxa, Peirosaurus torminni and Microsuchus schilleri. We concluded that terrestrial notosuchians may have lost osteoderm ornamentation due to the lower thermal conductivity of air and reduced heat loss in a terrestrial environment compared to what happens in water. Among these notosuchians, we hypothesize that large terrestrial baurusuchids maintained a stable body temperature due to thermal inertia, whereas small notosuchians took advantage of the early morning sun exposure to warm up and stayed in terrestrial burrows during periods of intense solar radiation. Finally, unlike the almost motionless behavior of freshwater crocodiles, fully marine Metriorhynchidae probably lost osteoderms because they constantly swim, generating heat by muscular contraction, so osteoderms with a thermoregulatory function for heat absorption were no longer positively selected.

Heat loss reduction and tap temperature equalization of a centralized domestic hot water system in a modernized pre-WWI residential building

Savings potentials in Domestic Hot Water (DHW) systems are very often overlooked, as these systems are designed to require as little maintenance as possible. The present work therefore focuses on the optimization of a DHW circulation system in a modernized pre-WWI multistory residential building in Vienna, Austria. To minimize the heat losses of the system and reduce the natural gas consumption for DHW production, a simple approach was chosen and implemented by installing and adjusting (i) a plug-in type timer switch and (ii) a plug-in type temperature switch to control the operation of the DHW circulation pump. In terms of piping and insulation, the DHW system was not modified whatsoever. Measurements were carried out to test the suitability and effectiveness of the selected concepts. The data obtained were evaluated in terms of reproducibility, DHW system heat losses and primary energy savings, as well as user comfort (tap temperature progression) and health and safety aspects. The results show that the implementation of a widely available and inexpensive temperature switch for controlling the DHW circulation pump led to remarkable DHW system heat loss reductions in the range of 20–30%, which corresponds to primary energy savings of 15–20%, with no negative impact on user comfort and DHW safety compliance. The share of electrical energy savings due to the reduction of the operating time of the circulation pump is negligible, as are the costs of the installed equipment of the presented energy efficiency measure.

Sustainable Greenhouse Covering Materials with Nano- and Micro-Particle Additives for Enhanced Radiometric and Thermal Properties and Performance

This review aims to provide a comprehensive overview of nano- and microscopic materials that can provide thermal radiation insulation without reducing visible light transmittance, thereby reducing heat loss and conserving energy in greenhouses. We also reviewed the radial and thermal properties of greenhouse covering materials. Fillers, colorants, reinforcers, and additives, as well as glass, plastic film, and plastic sheet materials, were discussed. Additionally, by searching for keywords like insulation film, insulation agent, and infrared insulation, compounds based on graphene and fullerene as well as phase transition materials (PCMs) that may be used for radiation insulation, we proposed their potential use in greenhouse covers. They can be divided into semi-transparent photovoltaic (PV) materials, zinc oxide-based film fillers, and silica filter films. We discussed the radiation heat insulation and light transmission characteristics of these materials. Nano-synthesis techniques were also investigated. Based on latest advances in the literature, future developments in the micro- and macroscale synthesis of nanomaterials will enable additional innovations in covering materials for greenhouse structures. A limiting factor, though, was the high sensitivity of PVs to external climatic and meteorological variables. The ability of materials used to make greenhouse covers to control the microclimate, reduce CO2 emissions, use less energy, and increase agricultural productivity, however, cannot be disputed. Similar to this, a thorough examination of the uses of various greenhouse technologies reveals that the advancements also have financial advantages, particularly in terms of reducing greenhouse heating and cooling expenses. The PCMs, which decreased greenhouse-operating costs by maintaining constant ambient temperatures, provide ample evidence of this.

ASSESSMENT OF THE EFFECT OF STRUCTURAL CHANGES IN UKRAINE’S DISTRICT HEATING ON THE GREENHOUSE GAS EMISSIONS

Introduction. The energy sector makes the largest contribution of about 65% of the total amount to greenhouse gas (GHG) emissions in Ukraine. District heating systems (DHS) as an energy subsector are a significant source of GHG emissions as a result of the combustion of fossil carbon fuels (natural gas, coal, petroleum products, peat, etc.).Problem Statement. Due to its obvious advantages, DHS will continue to develop with the use of advanced te chnologies that allow a significant increase in the efficiency and a reduction in heat losses, and accordingly ensure the lowest cost of heat energy for consumers. However, at the moment, no forecast has been made for the dyna mics of Ukraine’s DHS fuel balance, the heat generation structure, and, accordingly, GHG emissions until 2050.Purpose. The purpose of this research is to estimate the impact of structural changes in the DHS on the greenhouse gas emissions.Material and Methods. Publications in scholarly research journals, official documents, statistical data, methods of statistical and comparative analysis have been used. Calculations have been made with the use of the Methodology of the United Nations Intergovernmental Panel on Climate Change (UN IPCC).Results. Changes in the fuel balance and the generation structure of DHS of Ukraine have been forecasted. According to the forecast results, the natural gas consumption will decrease 1.4—2 times, while that of coal will fall 1.4—5.9 times. Petroleum products will not be used in DHS after 2040, but the electricity consumption will increase 7.7—19 times. At the same time, the biomass consumption will increase 2 times, and that of solar energy will grow 77 times, as compared with 2020. In 2050, the GHG emissions from DHS will amount to 3.9—6.9 million tons of CO2-eq., depending on the DHS structural dynamics scenario.Conclusions. The forecast of the structure of Ukraine’s DHS heat energy generation has predicted a 4.4 times reduction in the greenhouse gas emissions by 2050 for the optimistic and 2.5 times reduction for the pessimistic scenario of the DHS development, as compared with 2020.

Building energy and exergy analysis of the light-weight roofs compared with the traditional ones in different climates

A significant research gap exists concerning the thermal properties of lightweight roofs, as extensive investigations have predominantly focused on their mechanical characteristics. However, there is a notable dearth of studies addressing the thermal behavior of lightweight roof systems. The comprehension of thermal properties in lightweight roofs is of paramount importance, as it enables the promotion of energy-efficient design practices. The absence of comprehensive research in this domain constrains the optimization of thermal insulation mechanisms within lightweight roof constructions. Consequently, this hinders developments aimed at reducing energy consumption in buildings. To bridge this research gap, this study investigates the thermal performance of two lightweight roofs called waffle slab and bubble deck in three different climates, and compare them with conventional cement block roofs. Results revealed that Valencia had the lowest heating load due to its moderate climate, while Denver showed the minimum cooling load due to colder temperatures. The bubble deck roof outperformed other roofs in terms of heat loss reduction, achieving an average of 76% in winter and 41% in summer. Additionally, the bubble deck roof demonstrated the best overall efficiency (72% on average) and improved thermal comfort during summer, with lower energy consumption. Exergy analysis showed that the bubble deck roof significantly reduced input and output exergy, indicating its superior energy conservation capabilities compared to waffle slab and cement block roofs. These findings emphasize the potential benefits of lightweight roofs, particularly the bubble deck, in enhancing energy efficiency and occupant comfort.

Thermal performance of double-layer pipe-embedded envelope with low-grade energy for heating

Heat dissipation through a non-transparent envelope contributes significantly to the heating load during winter. The traditional single-layer pipe-embedded external wall (SPEW) can utilize low-grade energy to reduce the heat transfer through the envelope but can hardly be used for direct room heating. This study proposes a double-layer pipe-embedded external wall (DPEW) to utilize low-temperature hot water to reduce heat loss and provide indoor heating in winter. A numerical model of DPEW is developed to analyze its heat transfer performance. After experimental validations, the model is used to investigate the heat transfer performance of DPEW with different water temperatures, ambient temperatures, and envelope structures. The results show that (1) for the outer pipes of DPEW, water with a temperature lower than the room temperature (e.g., 12 °C) can be employed to reduce heat loss through the wall; for inner pipes of DPEW, water with a temperature slightly higher than the room temperature (e.g., 22 °C) can be employed for direct room heating; (2) the insulation layer thickness of the DPEW can be reduced to be significantly smaller than that of a conventional wall; an insulation layer between the two layers of embedded pipes is necessary to reduce heat transfer between water pipes; (3) the effect of water temperature on the heating capacity of DPEW is more significant than that of ambient temperature; increasing the pipe diameter and decreasing the pipe spacing can improve the heating capacity of DPEW.

Exergy analysis and optimization of multiple injection parameters of a diesel engine with Taguchi method

ABSTRACT Multiple injection parameters have a significant effect on performance and emission formation in diesel engines. This study presents the optimization of these parameters with Taguchi method for different engine operating conditions. The experiments were conducted using four injections per cycle named Pilot1 (P1), Pilot2 (P2), Main (M), and Post (Po). The input parameters considered were injection timings and fuel quantities for each injection, while the output parameters were brake specific fuel consumption (BSFC) and nitrogen oxides (NOx) emissions. According to the results, the analysis of variance (ANOVA) shows that the durations of the P2 (D_P2) and Po (D_Po) and the start of the Main (SOI M) injection are very significant on BSFC and NOx emissions as independent of the engine speed. Based on contribution ratios at 1750 rpm and 2250 rpm operating conditions, D_Po is the most effective parameter on BSFC with 47.28% and 51.30%, while D_P2 has the greatest impact on NOx emissions with 37.96% and 61.80%, respectively. It is found from the optimization model obtained by using the Signal/Noise (S/N) ratios that injecting 5% of the total fuel in the post-injection phase could simultaneously improve BSFC and NOx emissions. Furthermore, the optimization model generally reduces heat loss exergy, exhaust exergy, and exergy destruction compared to the experimental values.