Exhaust Temperature Research Articles

Computational exploration of single-fuel reactivity controlled compression ignition engine by integrating dimethyl ether/steam on-board reforming

A single-fuel dimethyl ether reactivity-controlled compression ignition engine system was established by integrating dimethyl ether/steam on-board reforming. For the dimethyl ether reforming reactivity-controlled compression ignition engine system, the product of dimethyl ether reforming (including the generated syngas and unreacted dimethyl ether) was provided through the intake port of the reactivity-controlled compression ignition engine, while the high-reactivity dimethyl ether was directly introduced into the cylinder to realize the reactivity stratification. In this study, computational investigations of dimethyl ether reforming and syngas/dimethyl ether reactivity-controlled compression ignition engine were respectively realized by the COMSOL software and the KIVA-3V code. The influences of the exhaust valve opening timing, the premix ratio, and the reformer number on the performance of the reformer and the reactivity-controlled compression ignition engine were studied. The results indicated that the earlier exhaust valve opening timing and the more reformer number are beneficial for the dimethyl ether reforming and energy recovery, and the effect of the premix ratio is relatively minor. For the test system, the highest exhaust energy that can be applied for the dimethyl ether reforming is around 25 %, and 8.8 % of the exhaust energy can be recovered into the fuel energy to realize the increase of the fuel energy. The highest conversion rate of dimethyl ether to syngas is 78 %, and the fuel energy is increased by 6.37 % after the reforming. With the introduction of the fuel reforming system, the improvement of the system thermal efficiency is between 0.52 % and 1.44 %. To realize the moderate, efficient, and clean combustion of the dimethyl ether on-board reforming reactivity-controlled compression ignition engine, the dimethyl ether conversion rate should be further improved at a lower exhaust temperature.

Raw Jojoba Oil as a Sustainable Fuel to Diesel Engines and Comparison with Diesel Fuel

Raw Jojoba oil was used in a direct-injection diesel engine without any engine modifications and compared with both diesel fuel and 50/50 raw Jojoba/diesel. The measured parameters included the rheological properties measured in the range of shear rate from 100 to 500 1/s. Distillation data were presented for raw Jojoba oil compared to diesel. The parameters included exhaust gas analysis, block vibration, sound noise, and the combustion pressure and its rise rate. Averaged pressure-crank angle, vibration, and its frequency spectrum and sound level were presented. Data also included brake power, specific fuel consumption, and exhaust temperatures for all fuels used. For Jojoba oil, the engine did not exhibit low power output or specific fuel consumption. Exhaust temperatures, smoke opacity, and NOx emissions were lower than diesel case. Noise for Jojoba was higher than diesel case. The engine block vibration was concentrated towards the low frequency range.

A detailed review of the analysis of the different types of materials such as aluminum alloys and cast-iron piston by comparing the results we can say among these which one of the pistons had better results

A piston is a component of reciprocating engines, pumps and gas compressors. It is located in a cylinder and is made gas-tight by piston rings. In an engine, its purpose is to transfer force from expanding gas in the cylinder to the crankshaft via a piston rod and/or connecting rod. The alloy from which a piston is made not only determines its strength and wears characteristics, but also its thermal expansion characteristics. Hotter engines require more stable alloys to maintain close tolerances without scuffing. The normal temperature of gasoline engine exhaust is approximately 650ºC (923ºK). This is also approximately the melting point of most aluminum alloys and it is only the constant influx of ambient air that prevents the piston from deforming and failing. For this purpose testing different types of materials such as aluminum alloys and cast iron piston. In this project we design the three models of pistons flat head, concave head & convex heads by using Pro-Engineer 5.0 software, and imported them to make analysis in ANSYS 11.0 soft ware. And find out the vonmisses stresses, total deformation, heat distribution, and heat flux. By comparing the results we can say among these which one of the piston had better results.

Experimental Investigation on OBD Signal and PN Emission Characteristics by Damaged-DPF Types of 2.0 L Diesel Vehicle

A diesel particulate filter (DPF) is an exhaust after-treatment device designed to capture and store exhaust particulate matter, such as soot and ash, to reduce emissions from diesel-powered vehicles. A DPF has a finite capacity and typically uses a substrate made of ceramic material that is formed into a honeycomb structure. Diesel particulate filters play an important role in diesel-fueled vehicles. Failure to maintain these filters can have significant consequences for vehicles. In this study, we investigated the failure type in cordierite DPF substrates. In addition, we experimentally characterized the particle number (PN) emission and on-board diagnostics (OBD) signal of a 2.0 L diesel-fueled vehicle generated by three types of DPF failure (crack, melting, and hollow). Specifically, X-ray photography analysis of the cordierite DPF was performed. The PN and OBD signals were assessed via the KD-147 vehicle driving mode and measured using a DMS-500 (PN measurement device) and global diagnosis tool (GDS) scanner (OBD diagnostic device), respectively. X-ray photography was used to characterize the internal structure of the three DPF-failure samples. A key result was that the maximum value of the OBD data, including airflow mass, boost pressure, and VGT actuator, was distinctly different for each DPF sample. The exhaust temperature gradient for the normal DPF and crack-damaged DPF followed the KD-147 driving pattern. This was because there was no volume damage inside the cordierite DPF substrates. However, in the case of the hollow and melting-damaged DPF, the volume inside the cordierite DPF substrates was reduced or the time for the exhaust gas to stay in the DPF substrates was decreased. The melting-damaged DPF continuously emitted the largest number of nanoparticles (of the order of 109 #/cc). This was regardless of the vehicle driving speed in the KD-147 driving mode. Eventually, an OBD-based algorithm to determine whether a DPF is damaged was derived in this study.

Activity of Catalytic Ceramic Papers to Remove Soot Particles—A Study of Different Types of Soot

Diesel soot particles are of concern for both the environment and health. To catalytically remove them, it is important to know their structure and composition. There is little described in the literature on how catalysts favor the combustion of different soot fractions. In this work, programmed temperature oxidation (TPO) experiments were carried out using Co,Ce or Co,Ba,K catalysts supported on ceramic papers. Soot particles were obtained by burning diesel fuel in a vessel (LabSoot) or by filtering exhaust gases from a turbo diesel engine in a DPF filter (BenchSoot), and compared with a commercial diesel soot: Printex U. Various characterization techniques were useful to relate the characteristics of both the soot particles and the catalysts with the TPO results. The maximum catalytic soot burn rate (TM) temperatures were in the range of diesel exhaust temperatures that would facilitate in-situ regeneration of the DPF. The Co,Ba,K catalyst showed a higher catalytic effect in LabSoot, as the latter exhibited the largest primary particles and the higher order of graphene layers, for which the potassium-containing catalyst improves the contact between soot and catalyst and favors the combustion of soot, while the Co,Ce catalyst preferentially enhanced the combustion of commercial soot by supplying active oxygen.

The impact of thermal status on emissions of a non-road diesel engine equipped with aftertreatment system under transient operation

The current study investigates the influence of hot and cold start on the emissions of a non-road diesel engine with an after-treatment system. The emissions were studied by experimental measurements on an engine during non-road transient operating conditions. These results indicate that the emissions of cold start are much higher than that of the hot start. The conversion efficiency of particular matter (PM) is only 33%, which is 31% lower than that of the hot start. Besides, the conversion efficiency of PM is weak under the cold start, and high exhaust flow, and the phenomenon of blow-off is prone to happen. The conversion efficiencies of NOx, HC, and CO are 86%, 79% and 63%, respectively, which differs from the hot-start conversion efficiency by 10%–16%. And their differences are mainly reflected in the early stage (0–600 s). Overall, the exhaust temperature and flow are important factors that affect the conversion efficiency of the after-treatment system, and the specific process was discussed in this paper. These provide enlightenment/direction for the emission reduction of non-road diesel engines.

Experimental study of R290 replacement R134a in cold storage air conditioning system

R290 refrigerant offers good environmental protection and thermodynamic characteristics. The feasibility of R290 replacing R134a was summarized through theoretical analysis and experimental tests in this paper. A coiled ice storage experimental test platform was built, and the performance of R290 and R134a cool storage air conditioning systems was analyzed. The experimental analysis confirmed that the R290 system has a higher volumetric refrigerating capacity, and the system COP (coefficient of performance) is comparable to the R134a system. At the same evaporation temperature, the pressure ratio and exhaust temperature of the R290 system are lower than those of the R134a system. In addition, the charge amount of the refrigerant can have an impact on cold storage performance. It was found that the optimal charge range of R134a is 1300–1400 g, and that of R290 ranges from 500 to 600 g. The optimal charge amount for R290 is only 43–46% of R134a. A lower charge amount is beneficial to reduce the explosion risk of the R290 cool storage air conditioner. Under the optimal charge, the R290 system has a fast cooling rate and shorter cooling storage time, and the average specific refrigerating effect is increased by approximately 52% compared with R134a.

Frost prevention research of the enthalpy wheel in air conditioning systems and industrial heat recovery systems

Enthalpy wheels are often used for air dehumidification and waste heat recovery. Application scenarios include air conditioning systems and industrial systems.Frost formation inside the enthalpy wheel is common in cold climates and has serious impacts on operational reliability and heat recovery performance. It is found that frost type, frosting area and frosting limit vary between different scenarios. Experimental and numerical investigations are conducted in the present research. For a certain wheel, inlet parameters of supply air and outlet parameters of exhaust air are the key factors influencing frosting formation. The enthalpy wheel will operate regularly without frost formation if exhaust temperature is higher than the frosting limit. Reducing the enthalpy wheel rotation speed below 6 rpm is an effective method to prevent the enthalpy wheel from frosting, but heat recovery efficiency is correspondingly reduced. Industrial systems are less affected by the cold climate, especially at higher exhaust air temperatures. Even if the climate temperature drops to −30 °C, the heat recovery efficiency can still exceed 85%. The research is anticipated to be useful for the application of enthalpy wheels in cold climates.

Model Investigation of Natural Gas Engine Performance to Achieve Variable Heat/Electricity Ratios for a CCHP System by Varying Spark Ignition Timings

For electric reliability and to save energy, the distributed power generation combining cooling and heating supply called a CCHP system for architectures has many potential advantages and is widely adopted to provide electric power and to satisfy local heating and cooling loads by waste heat recovery with low carbon intensity. However, the current CCHP system usually has a fixed ratio of the power and heat due to the features of its power unit, which leads to difficulties in the load management. In this paper, based on the operation of an internal combustion engine fueled with natural gas, a novel method is proposed and studied to achieve a controllable rate of heat/power to meet different load requirements of the electricity and heat (cooling or heating loads). By varying the ignition timing of the spark ignition engine, the combustion process within the cylinder can be adjusted to occur at different crank angles so that the engine crank shaft output power (related to the generated electricity) and the heat from the exhaust gas are changed accordingly. To study the effects of ignition timing on engine power and exhaust heat energy, a two-zone model was established with a predictive combustion model. The changes in the combustion process, output power, exhaust gas temperature, and heat energy were mostly our concern. The results show that the heat/electricity ratio can be adjusted from normally 1.0 to 1.6, and they can be controlled independently under partial load operating conditions. To solve the potential thermal failure of the turbine, the extraordinarily high exhaust temperature will be adjusted by compressed air.

Fast Diesel Aftertreatment Heat-Up Using CDA and an Electrical Heater Between 1.2 and 5.0 kW

Commercial vehicles require fast aftertreatment heat-up in order to move the selective catalytic reduction catalyst into the most efficient temperature range to meet upcoming NOX regulations while minimizing CO2. This study is a follow-up study using an electric heater upstream of a LO-SCR followed by a primary aftertreatment system having an engine equipped with cylinder deactivation. The focus of this study is to minimize the maximum power input to the e-heater without compromising tailpipe NOX and CO2. A system solution is demonstrated using a heavy-duty diesel engine with an end-of-life aged aftertreatment system targeted for 2027 emission levels using various levels of controls. The baseline layer of controls includes cylinder deactivation to raise the exhaust temperature more than 100°C in combination with elevated idle speed to increase the exhaust mass flow rate through the aftertreatment system. The engine load is adjusted to compensate for generating electrical power on the engine. The combination of electrical heat, added load, cylinder deactivation, and elevated idle speed allows the aftertreatment system to heat up in a small fraction of the time required by today’s systems. This work was quantified over the cold federal test procedure, hot FTP, low load cycle (LLC), and the U.S. beverage cycle showing improved NOX and CO2 emissions. The improvement in NOX reduction and the CO2 savings over these cycles are highlighted.

Optimization on the jet characteristics of the main nozzle of hot-blowing snow removal device

The exhaust devices used by snow removal vehicles are mainly based on hot-blowing snow removal. Due to the inherent characteristics of the turbojet engine such as low flow rate and high exhaust temperature, the modified hot-blowing snow removal device has problems of low snow removal efficiency and the possibility of ablation and damage to the road surface. In order to solve the problem, transforming the turbofan engine with a high flow rate and a low exhaust temperature into a hot-blowing snow removal device is an important improvement to achieve efficient and safe snow removal operations. In order to convert a medium bypass ratio turbofan engine into a hot-blowing snow removal device, the computational fluid dynamics (CFD) software CFX was used to analyze the internal and external flow field characteristics of the main nozzle of an exhaust device under the 60 % rated condition of the engine. The effective area sizes of the jet velocity and temperature predicted by the external flow field were used to optimize the layout of the main nozzle.

Study on the performance of an energy-efficient three-stage auto-cascade refrigeration system enhanced with a pressure regulator

This paper proposed a modified three-stage auto-cascade refrigeration cycle (MTARC) associated with an intermediate pressure regulator. The energy and exergy analyses indicate that the MTARC can acquire lower evaporating temperature, greater cooling capacity and higher COP. Under a typical operating condition, the MTARC using the alternative ternary zeotropic mixture of R1234yf/R41/R14(0.66/0.17/0.17) has an evaporator inlet temperature of −90.90 °C, COP of 0.4509 and exergy efficiency of 40.67%, which are 4.63 °C lower, 32.93% and 15.38% higher than those of the conventional three-stage ARC, respectively. Further research shows that with the decreasing intermediate pressure, the thermodynamic performance of the MARC can be improved significantly, but the compressor exhaust temperature also increases. When the intermediate pressure decreases from 1.8 MPa to 1 MPa, the cooling capacity, COP and exergy efficiency of the MTARC increase by 30.34%, 22.10% and 13.79% respectively, while the exhaust temperature increases 18.59 °C from 116.66 °C to 135.25 °C, which indicates that the selection of intermediate pressure needs to be comprehensively considered. The proposed new approach is valuable for optimizing the design and application of the refrigerator at an ultra-low temperature level of −80 °C.

Research on Mobile Machinery NOx Emission Control Based on a Physical Model and Closed-Loop Control

Mobile machinery means a power-driven vehicle that is specifically designed and constructed to perform work on or off the road. To reduce the nitrogen oxide (NOx) emissions that come from mobile machinery, a combination of a physical model and closed-loop control is applied to the selective catalytic reduction (SCR) system. Based on the design of the variable cross-section extended exhaust structure, the differential pressure measurement was achieved, and the physical model of the exhaust flow based on the differential pressure was established. Based on the analysis of the heat and mass transfer process of the SCR catalyst, a prediction model for the internal temperature field of the catalyst was established by combining the upstream and downstream exhaust temperature sensors. Using the SCR downstream nitrogen oxides signal and the proportional–integral–derivative (PID) closed-loop control algorithm, segmented PID closed-loop control under the large hysteresis response of the SCR system was realized. The above algorithms were used to form the control code through MATLAB/Simulink and downloaded to the embedded microprocessor. The test results show that the established model can realize the real-time calculation of the exhaust gas flow rate and the internal temperature of the catalyst. Under steady-state conditions, the calculation error of the exhaust flow rate is less than ±3%, and the calculation error of the catalyst temperature is less than ±5%. Under transient conditions, the calculation error of the exhaust flow rate is less than ±9%, and the calculation error of the catalyst temperature is less than ±8%. The nitrogen–oxygen signal-based PID closed-loop algorithm can improve the nitrogen–oxygen conversion efficiency and control accuracy of the model.

Structured neural-network-based modeling of a hybrid-electric turboshaft engine's startup process

Given its highly nonlinear and multi-physics-coupling nature, modeling the startup process of a turboshaft engine has always been a difficult task, which is further aggravated on a turboshaft engine in a hybrid-electric system. With sufficient data from bench experiments, this article establishes a data-driven numerical model to simulate the startup process of a hybrid-electric turboshaft engine. Neural networks are organized hierarchically to estimate three key parameters of the engine system: engine speed, leftover torque, and exhaust temperature. Specifically, on exhaust temperature, different neural networks were tried and compared. The networks were built, trained, and tested in sections, and then tested as a whole. Compared with the mechanism-based methods, the model proposed in this article has a simple structure and can be built automatically. According to the running tests, the proposed method can give accurate results at a fast speed using small hardware resources, showing great potential as a reference model on real-time control units.

Performance Analysis of an Absorption Heat Pump System for Waste Heat and Moisture Cascade Recovery from Flue Gas.

The typical flue gas exhaust temperature of coal-fired boilers is up to 150 °C. There is a considerable amount of waste heat that cannot be efficiently recovered. This study describes a zero-energy consumption absorption heat pump system that can improve the thermal efficiency and recover moisture. In the proposed system, lithium bromide solution serves as the recyclable heat-transfer medium, which absorbs sensible heat at the outlet of the air preheater by a generator. The latent heat of the flue gas is absorbed by an evaporator, and the condensate water appears. Theoretical investigation and mathematical models are built. Meanwhile, the operating parameters of the system are displayed. The results showed that the acid dew point of flue gas is related to the water content. The sorption heat pump efficiency (coefficient of performance) increased to 1.64. Compared with the two-stage heat exchanger system, 24.4 t/h condensate water and 47.21 MW waste heat were recovered. The flue gas temperature at the chimney entrance was reduced by 4.18 °C.

The effect of using the WCO biodiesel as an alternative fuel in compression ignition diesel engine on performance and emissions characteristics

Recently, the need for using a substitute fuel for petroleum fuel in diesel engines becomes an utmost necessity, However, the petroleum fuel is considered a non-renewable source and has some environmental side effects. The price of petroleum fuels changes according to the world economic and political problems. Engine emissions should be reduced and fit the governmental guidelines, the harmful emissions produced from engines have extreme environmental side effects, one of these effects is called the global warming which causes a global increase in the world temperature. In this study, the biodiesel extracted from the Waste Cooking Oil (WCO) is generated as a substutute for the diesel fuel. In the process of the biodiesel production, catalytic transesterification reaction is used to change WCO to methyl esters by adding low alcohol concentration. The produced biodiesel will be prepared for using as a fuel blend along with the commercial diesel fuel and using it to petrol the four-stroke direct injection diesel engine without any modification to original fuel system. The engine will be tested experimentally with varying loads at fixed speed of 1400 rpm with a natural aspiration process, using blends of (B20 [is composed of 20% biodiesel and 80% diesel], B40 [is composed of 40% biodiesel and 60% diesel], B60 [is composed of 60% biodiesel and 40% diesel], B80 [is composed of 80% biodiesel and 20% diesel] and pure diesel). The effect of the use of different biodiesel blends has been investigated and tested on the performance of the engine and emissions. The experimental findings clarify that the diesel engine can be run with different blends of diesel and biodiesel at the same operating condition with decreasing brake thermal efficiency by 9.6 %, decreasing exhaust temperature by 7.6% and increasing brake specific fuel consumption by 16%.

Computational Study of Interaction and Removal of Benzopyran by Anatase Titanium Dioxide Nanoparticle

Most gas emissions by motor automobiles include unburned hydrocarbons, carbon monoxide, and other oxides (NxOy, SOx, etc.). There are many hydrocarbon compounds in car exhaust, such as benzopyran, formaldehyde, butadiene, and so on. In this study, anatase titanium dioxide nano-particles (aTiO2-NPs) filters are investigated to prevent the entry of unburned hydrocarbons. Benzopyran is one of the most important aromatic compounds in car exhaust gases, which is very dangerous. The probability of its interaction with titanium oxide nanoparticles is simulated and evaluated according to chemically active sites of aTiO2-NP. Calculations were performed using the DFT calculation on the basis set LC-ωPBE/6-311 + G** method. The obtained data show that Ti–O chemically active site has a greater tendency to adsorb benzopyran due to its polarity (Dipole moment for 3rd of Ti–O = 6.93 D). By adsorbing benzopyran in the Ti–O position, the gap energy of aTiO2-NP decreases (E g = 3.09 eV), and its conductivity increases. The results showed that the nano-adsorbent of aTiO2-NP has high efficiency in the adsorption of benzopyran from the environment. Due to the exhaust temperature of the car and the photocatalytic properties of the aTiO2-NPs nano-adsorbent, it can be used as an adsorbent with high performance and longevity, and good stability in high-temperature ranges.

Estimation of the effect on air quality of retrofitting SCRT on urban buses in Copenhagen

ABSTRACT This study estimates the effect on air quality of retrofitting SCRT on about 300 urban buses in Copenhagen from September 2015 to March 2016. The retrofitted buses were of Euro III, Euro IV and EEV emission standards. The specific SCRT technology applies ammonia as injected into the exhaust as a gas as opposed to normally as a liquid (urea). This technology is more efficient in reducing NOx emissions, especially under urban driving conditions with relatively low exhaust temperatures. The estimation of the effect is based on air quality model calculations for 98 selected busy streets in Copenhagen for 2015 based on, among others, information from the Zealand public transport agency about buses with and without retrofitted SCRT. More detailed analyses were conducted for two of the streets where fixed air quality measuring stations are located in Copenhagen. Furthermore, a before-after analysis of the development of measured concentrations at fixed measuring stations was carried out to isolate the effect of the retrofitted SCRT. The model calculations showed substantial reductions in emissions of NOx and exhaust particles from each bus (90%) but low reductions in concentrations of NO2, PM2.5 and PM10, respectively 3% for 98 streets on average for NO2, and 0.1%[0.2%] for PM2.5 and 0.07%[0.1%] for PM10 for H.C. Andersen Boulevard and [Jagtvej]. Based on the analysis of trends in the measurements it was not possible to isolate an effect of SCRT on urban buses in Copenhagen probably due to the large variations in meteorology affecting the variations in concentrations.

Combustion and emission characteristics of diesel with different distillation ranges on the China-VI diesel engine

In this study, hydrocarbon compositions of two types of diesel with different distillation range indexes T90 and T95 were analyzed by gas chromatography-mass spectrometry combined with gas chromatography-field ionization-time of flight mass spectrometry (GC-FI TOF MS), to evaluate the effect on the combustion characteristics and exhaust emissions of three diesel engines. The diesel featured by lower T90 and T95 can improve diesel volatilization performance, shorten the ignition delay time and increase the engine combustion efficiency. The BSFC can be reduced by 0.7%, and the CO2 emission can be reduced by 0.69% (WHTC), and 0.94% (WHSC), respectively, as the increasing low carbon numbers of alkane (C8-C20), monocyclic cycloalkane (C7-C16), bicyclic cycloalkane (C9-C15) and tricyclic cycloalkane (C10-C19) and the decreasing of heavy components such as indane, indene, naphthalene, biphenyl, phenanthrene, etc. The diesel with lower T90 and T95 can reduce the original NOx emissions and the exhaust temperature after the vortex, then decrease the combustion temperature in the cylinder. Finally, tailpipe outlet NOx emissions of the China-VI diesel engine decreased by 7.64% (WHTC) and 12.93% (WHSC), respectively. Besides, the diesel with lower T90 and T95 can reduce the content of PAHs with π bonds, and generate a more uniform fuel–air mixture in the cylinder, thus achieving emission reduction of PM by 14.58% (WHTC) and 37.31% (WHSC), and PN reduction by 25.74% (WHTC) and 14.09% (WHSC), respectively.

Study on Characteristics and Control Strategy of Diesel Particulate Filters Based on Engine Bench

The ignition temperature of a diesel oxidation catalyst (DOC) and the internal temperature-field distribution of the diesel particulate filter (DPF) during active regeneration are investigated during an engine bench test in this study. Based on the dropped to idle (DTI) test, a test method is developed to determine the safe regeneration temperature of the DPF. The results show that when the inlet temperature of the DOC is more than 240 °C, the DOC begins ignition and reaches the target temperature of 600 °C set for active regeneration of DPF; when the inlet exhaust temperature of the DOC is between 240 and 280 °C, a higher injection rate is required to reduce the secondary pollution of HC and thus make the DPF reach the set target temperature as soon as possible. The active regeneration process of the DPF is divided into three stages. During ignition, the temperature of the DPF inlet and outlet increases rapidly and successively. The internal and outlet temperatures of DPF during regeneration are approximately 50 °C higher than the inlet temperature. At the end of regeneration, the DPF inlet to outlet temperature drops rapidly. A feed-forward design and feedback algorithm are used to verify the change in the target regeneration temperature. The overshoot of the DPF control strategy was less than 3%, and the steady-state temperature control error was less than 20 °C. The results of this study provide a basis for the safe control of DPFs’ active regeneration temperatures.