Increase In Thermal Efficiency Research Articles

Experimental examination of the effect of thermal barrier coating in a 2-stroke gasoline engine on recovery performance in exhaust waste heat recovery system with thermoelectric generator and engine performance

In internal combustion engines, while the decrease in in-cylinder wall temperature increases the amount of energy passing towards the cooling system, it decreases temperature and pressure at the end of compression and accordingly reduces thermal efficiency of the engine. Moreover; combustion chamber elements are exposed to chemical corrosion and deformation as a result of uncompleted combustion in the cylinder. With thermal barrier coating application, the energy lost in cooling system will decrease and exhaust temperatures will increase in 2-stroke engines. Placement of a waste heat recover system with thermoelectric generator into the exhaust system can provide exhaust waste heat recovery and increase thermal efficiency of the engine. There is no study in the literature, which examines waste heavy recovery systems with thermal barrier and thermoelectric generator altogether. In this article, yttria stabilized zirconia coating has been applied by means of plasma spraying method in the combustion chamber of a 2-stroke gasoline engine, and effect of thermal barrier coating application on engine performance and exhaust waste heat recovery system has been examined experimentally. According the results of the experiment, maximum engine power has increased by 6.23%, maximum engine torque has increased by 6.02%, and specific fuel consumption decreased by 5.56%. While the exhaust temperatures have increased by 78.5 °C at maximum by means of thermal barrier coating application; by means of thermal barrier coating application with waste heat recovery system with thermoelectric generator, a higher waste heat recovery has been obtained by 64.8%.

Evaluation of an integrated electric power generation system with natural gas engines operating in dual mode through heat recovery with thermoelectric devices for hydrogen production

In the present investigation, an environmental, thermal, economic, and social analysis of an integrated system is carried out, which has as its function the production of hydrogen through the recovery of residual thermal energy from exhaust gases. The proposed integrated system consists of a thermoelectric generator and a hydrogen production bench based on the water electrolysis process. For the development of the research, an internal combustion engine fueled with natural gas was used, operating under four load conditions (25%, 50%, 75%, and 100%). From the environmental assessment, it is demonstrated that the implementation of the integrated system allows a decrease of 12.30%, 6.26%, and 7.90% in CO, CO2, and HC emissions. However, the addition of hydrogen causes a 9.9% increase in NOx emissions. Additionally, the implementation of the integrated system allows a 4.9% decrease in brake specific fuel consumption and a 4.9% increase in engine thermal efficiency. The improvement in engine thermal performance contributes to the 7% reduction in engine operating costs. On the other hand, it demonstrates an 8.7% reduction in the environmental and social impact cost and a 9% reduction in the ecological cost. Additionally, the integrated system minimizes the cost of environmental and social impact, as well as the ecological cost of polluting gases CO, CO2, and HC. The mixture of natural gas and hydrogen allows for a 4.70% and 7.59% increase in pressure and maximum heat release rate. In general, the proposed integrated system is a way to harness the thermal energy of exhaust gases for hydrogen production. In this way, it is possible to obtain an auxiliary fuel that improves the efficiency of the combustion process of the natural gas engine. This allows for minimizing energy losses in self-generation activities in Colombia, achieving better energy management and a reduction in operating costs.

Thermodynamic evaluation of 2026 Power Unit technical regulation changes in Formula 1

Federation Internationale de l'Automobile (FIA) has announced a Power Unit (PU) Regulation change for its Formula 1 (F1) Championship that will become valid from the 2026 season in pursuit of carbon neutralization and a higher commercial value. The change includes a full switch to sustainable fuel and an increase in the power of the electric power output to the cars axles but removed energy retrieving and recovery from the turbocharger. The choice to use fully sustainable fuel will lead to a richer burn. On the other hand, the increase in the hybrid system capacity will outweigh the removal of energy retrieving and recovering from the turbocharger and cause an overall increase in thermal efficiency. Also, the changes are bringing a cost reduction for PU suppliers, which is an attraction for them. The increase in electric power will also integrate the car with new driving characteristics. This paper focuses on respective reviews of the 2023 and 2026 F1 PU Technical Regulations and gives an evaluation of the process for the improvements.

3D thin-film nanofluid flow with heat transfer on an inclined disc by using HWCM

Abstract Momentum and heat transmission influence the coated physical characteristics of wire product. As a result, understanding the polymeric movement and heat mass distribution is crucial. An increase in thermal efficiency is necessary for the wire covering technology. So, the aim of this work is to investigate the influence of nanomaterials on the heat and mass transport processes in wire coating analyses. A thin film nanofluid is used to investigate heat and mass transfer in three dimensions over a rotating inclined disc. Both the suction and injection effects of nanofluids and the thermal radiation of their fluxes are taken into account. By employing similarity variables, the set of governing equations can be transformed into a differential equation system. The necessary differential equation system is solved using the Haar wavelet collocation method. Plots and observations of the velocity distribution, concentration, and thermal fields within the boundary layer across an inclining, steadily rotating plane are made. Flow characteristics change as a result of varying embedded factors such as S , Sc , N b , Pr , S,{\rm{Sc}},{N}_{{\rm{b}}},\Pr , and thermophoretic parameters. Evidence suggests that as the number of rotation parameters grows, the thermal boundary layer weakens.

A novel solar-driven waste heat recovery system in solar-fuel hybrid power plants

Solar-fuel hybrid power generation can effectively reduce pollutants in fuel power plants and facilitate the efficient utilisation of solar energy. This study proposes a novel solar-driven waste heat recovery system for solar–fuel hybrid power plants. New system is integrated with parabolic-trough solar collector to drive the heat pump and optimise air pre-heating, offering unique advantages: solar energy amplification and upgraded utilisation. For a 600 MW unit, solar energy in new system generates an electric power of 9.0 MWe with a 0.67 % increase in thermal efficiency, almost twice that of conventional system. With waste heat recovery, the new system exhibits a solar-to-electricity efficiency of 42.12 %. The new system can increase boiler exergy efficiency from 47.78 % to 48.35 %, and decrease exergy loss of air pre-heating to 7.6 MWe. The essential energy saving mechanism of the new system can be attributed to the optimisation of air preheating. Owing to high thermal performance, new system can yield a net benefit of 13.82 million CNY/y, which is 2.6 times that of conventional system. The findings of this study can help for better understanding of solar energy amplification and and upgraded utilisation, thus opening new avenues for solar conversion in solar-fuel hybrid power generation systems.

Energy analysis and control scheme optimizations for a recuperated gas turbine with variable power offtakes/inputs

An innovative hybrid electric propulsion system (HEPS) is used for recuperated gas turbine (RGT) to avoid partial-load efficiency deterioration. Power offtakes/inputs of high and low-pressure shafts can be regulated by electric machines to achieve decoupling control in the innovative HEPS. The HEPS brings higher heating temperature in the combustor and significantly higher thermal efficiency at partial-load by optimizing the control scheme. A component-level model is used to conduct energy and performance analyses for RGT. The control scheme is optimized to enhance partial-load efficiency and protect RGT from temperature overrun, rotational speed overrun, and compressor surge.The optimal control scheme keeps the combustor exit temperature constant at the maximum restricted value to attain minimum combustor exergy loss under partial-load. The optimal control scheme brings smaller surge margins, but it successfully reverses the deterioration trend of efficiency with decreased load. The thermal efficiency of the original RGT decreases by 8.2 % as the load decreases from 100 to 40 %. The HEPS makes the efficiency curve of the RGT almost keep horizontal as the load ranges from 100 to 40 %. The specific fuel consumption decreases by 29.1 %, and the thermal efficiency increases by 11.5 % at 40 % load, compared to the original RGT.

Prediction of RCCI combustion fueled with CNG and algal biodiesel to sustain efficient diesel engines using machine learning techniques

This study used microalgae biodiesel as a high-reactive fuel directly injected along with various Compressed Natural Gas (CNG) energy shares (10, 20, 30, and 40%) as low-reactive fuel injected into the intake system. The experiments are performed in a single-cylinder, water-cooled, 1500 rpm, 3.5 kW power Compression Ignition (CI) engine under various loading conditions to examine the effects of CNG energy share on performance and emissions in Reactivity Controlled Compression Ignition (RCCI) combustion mode. The study found that the 30%CNG share decreased Nitrogen oxides (NOx) and smoke by 25 and 31%, as well as an increase in thermal efficiency of 4.35% in comparison to traditional biodiesel combustion. Finally, two machine learning (ML) models, namely the Gradient Boosting Regressor (GBR) and LASSO (Least Absolute Shrinkage and Selection Operator) Regression, were developed for predicting the dependent variables individually from the independent variables. Both the LASSO and GBR models achieved high accuracy with R2 values of 0.98–0.99 and relatively low Root Mean Square Error (RMSE) values.

Experimental Study on the Impact of Hydrogen Injection Strategy on Combustion Performance in Internal Combustion Engines.

Hydrogen is an ideal alternative fuel for internal combustion engines due to its fast combustion rate and near-zero carbon emissions. To further investigate the impact of the injection strategy on combustion performance under various excess air coefficients and loads, experimental methods were employed to systematically study injection timing, injection pressure, and dual injection. The results demonstrate that appropriately delaying hydrogen injection timing can improve the thermal efficiency by up to 2.6% and reduce NOx emissions of equivalent combustion by nearly 88%. While increasing the hydrogen pressure to 8 MPa does not directly enhance the thermal efficiency and emissions, it can reduce the injection pulse width by approximately 75%, allowing for more flexibility in delaying the injection timing. Delaying the secondary end of injection (SEOI) leads to a reduction of over 47% in NOx emissions for λ (excess air coefficient) values of 1.5 and 1.0. The combustion duration and ignition delay initially increase and then decrease with the delay in SEOI, depending on the movement state of the fuel jet. With the increase in secondary injection proportion (SIP), brake thermal efficiency increases by no more than 1%, but NOx is reduced by more than 43% for λ values of 1.5 and 1.0. In the case of ultralean conditions (λ = 2.3), increasing the SIP from 0 to 30% results in a nearly 14% increase in the peak heat release rate (HRR) and a 19% reduction in combustion duration.

Dynamic interdependence of comfortable thermal conditions and energy efficiency increase in a nursery school building for heating and cooling period

The paper studies the influence of building function and orientation, level of thermal insulation on energy efficiency and occupant thermal comfort dynamic interdependence. Energy state dynamic modelling of the typical preschool educational facility (Kyiv, Ukraine) was carried out with different levels of thermal comfort in each of the zones, taking into account occupants' activity, metabolism, clothing, etc. The research was conducted for the heating and cooling periods, taking into account the operational peculiarities of the building. Increasing the thermal resistance from the base version to the Swedish norms reduces energy consumption by 32% for the heating period, compared to the base version. The introduction of intermittent heating leads to a reduction of energy consumption by 14%, compared to the base version. Intermittent heating and ventilation and increased thermal protection to Swedish standards can reduce energy consumption by 42%. The investigation of comfort indicators revealed that during the transition period when the heating is turned off, electric heating of the premises is required to maintain the comfort conditions, which increases the heating energy consumption by 18%. Three different options for children's clothing in the summer period to avoid feeling cold were investigated.

Performance analysis and comparison of the spark ignition engine fuelled with industrial by-product hydrogen and gasoline

The global push for carbon neutrality in internal combustion engines has driven research into low-carbon or zero-carbon fuels for the transportation sector. Hydrogen, as a carbon-free, high-density, and secondary energy source, can be obtained on large scales during the petroleum refining process as industrial by-product hydrogen (IPH). In this work, the IPH is firstly used and tested in the spark ignition (SI) engine. In, addition, the impacts of operating and controlling parameters on the performances of the SI engine fuelled with IPH are investigated and compared with the engine fuelled with gasoline. The experimental results indicate that the CA 10 and CA50 locations of the SI engine fuelled with IPH initially advance and then retard with increasing load. Meanwhile, its brake specific gas consumption decreases, while the brake thermal efficiency (BTE) increases. The results demonstrate that NOx emissions of the test SI engine fuelled with IPH increase, while the CO and HC emissions reduce with increasing the load and remain relatively low under medium load conditions. The optimum spark timing of the SI engine fuelled with IPH achieves a balance between the BTE and emissions. In addition, the combustion phasing of the SI engine fuelled with IPH advances and its combustion duration shortens compared to the test gasoline engine. Additionally, the SI engine fuelled with IPH outperforms the gasoline engine in terms of fuel economy, and its BTE increases by 15.39% and 11.58% under loads of 2.5 bar and 5 bar, respectively. Compared to the gasoline engine, the NOx emissions of the test SI engine fuelled with IPH slightly increase while its CO and HC emissions are reduced by more than 90%.

A new heat pump-operated solar desalination unit integrated with an air recirculating room

In this paper, a new study was presented studying the effect of coupling a solar still and a heat pump to improve the performance of a solar still. Two setups of solar stills were considered one conventional and one modified using a heat pump coupled with a room containing a Trombe wall to hit two birds with one stone using the effect of cooling and condensing. Besides, some parameters were studied such as the heat pump compressor On and Off duration effect, water depth effect, and the cooling effect for the integrated room. Energy, exergy, and cost analysis were concluded in the manuscript. The findings revealed that, for a water depth of 15 mm and a compressor operation of 55 min. On and5 min. Off, the total amount of water produced was 9.896 L/m2, which represents an improvement of roughly 148.39 % compared to the conventional one. Furthermore, the daily exergy and thermal efficiency increase was evaluated as 49.86 and 82.78 %, respectively. Also, cost decreased by around 4.73 % and was computed as 0.0141 $/L. Finally, the integrated room of the Trombe wall system had a significant benefit since, during the hottest hour (1 P.M.), the cooling effect was 12.8 °C below the ambient, resulting in a temperature drop of over 30.4 %.

Performance characterization of a novel PV/T panel with nanofluids under the climatic conditions of Muscat, Oman

The study presents an experimental analysis of a novel mini channels-based Photovoltaic/Thermal (PV/T) panel with nanofluid flow. The design consists of a PV plate attached to an aluminum substrate absorber plate having minichannels grooved on it to act as a solar collector and cooling mechanism for PV. The proposed design was tested for thermal and electrical efficiencies under the working fluids of water, Al2O3, and SiO2 nanofluids at 0.1% and 0.2% concentrations in water and at a flow rate of 0.005 l/s to 0.045 l/s. The experiments were carried out outdoors in a real environment and the measurements were taken for PV surface and fluid temperatures, incidence solar flux, electrical voltage, and current produced. The PV and PV/T performance was compared, and a noticeable enhancement in electrical efficiency was observed with the proposed design as compared to the bare PV module, and an appreciable augmentation in thermal efficiency was noticed when nanofluids were applied. The maximum electrical and thermal efficiencies of PV/T with 0.2% Al2O3 nanofluid were 19.1% and 73.4%, respectively; whereas for bare PV panels, the electrical efficiency was 18.7%. The Al2O3 nanofluid at 0.2% exhibited more than a 10% increase in thermal efficiency compared to water as a working fluid in PV/T.

The effect of the properties of porous fillers on the performance of a PCM-based photovoltaic thermal system: A CFD study

In thermal systems, combination of PCMs with porous fillers with high thermal conductivity is a proper method to improve their performance. In photovoltaic thermal (PVT) systems, as porous fillers are introduced to the collector tube and PCM bulk, the thermal efficiency increases. Moreover, since the temperature of the PV unit has dropped, the electrical efficiency has improved too. However, the properties of the porous insertion, i.e., permeability and porosity, might affect the pumping work, and consequently, electrical efficiency. In the present study, the effect of metal foam insertions on thermal and electrical performances is analyzed using a computational fluid dynamics (CFD) method. The results show that installing metal foams with porosities of 0.70–0.94 inside the collector and PCM container of a PVT system improves the thermal efficiency without any considerable decrement in electrical efficiency. When copper foam with a porosity of 0.705 is installed within the collector and PCM tank, the highest thermal efficiency of 66.70% is achieved; while, when copper foam with a porosity of 0.94 is used, the maximum electrical efficiency of 13.24% is resulted.

Solar energy harvesting from the photovoltaic/thermal (PV/T) pavement: Energy performance analyses and comparison considering ground influence

Under the carbon neutrality targets, the easy-installation low-investment photovoltaic (PV) technology is vital, while the limited urban rooftop area and high building façade cost limit the onsite PV installation. Thus, harvesting solar energy from the road, namely pavement-integrated photovoltaic/thermal (PIPV(T)) technology, is promising. The 2D finite element PIPV(T) models are proposed and verified through the field test within 3% (cell temperature) and 7% (PV output) mean absolute percentage error. The parametric analyses on system designs (water tank volume, water velocity, water inlet temperature), weather conditions (solar irradiance, wind velocity), and ground boundary condition influence are conducted. The water inlet temperature acts as a minor factor, while tank volume and fluid velocity are crucial, i.e., a 32.76% thermal efficiency increase for a 125 L tank volume increase. Results show that over 0.2 L/s water flow rate is recommended for a 100 L water tank, and the solar irradiance increase adds to the thermal efficiency to 41.47% under 1000 W/m2 with 11.38% ground influence. The annual system performances for southern and northern metropolises are compared, with water tank variation considered. Results show that a small water tank leads to high temperature and low system thermal efficiency at 9.3% and 12.17% in Hong Kong and Beijing.

Study on the Effects of the Hydrogen Substitution Rate on the Performance of a Hydrogen–Diesel Dual-Fuel Engine under Different Loads

Due to having zero carbon emissions and renewable advantages, hydrogen has great prospects as a renewable form of alternate energy. Engine load and hydrogen substitution rate have a considerable influence on a hydrogen–diesel dual-fuel engine’s efficiency. This experiment’s objective is to study the influence of hydrogen substitution rate on engine combustion and emission under different loads and to study the impact of exhaust gas recirculation (EGR) technology or main injection timing on the engine’s capability under high load and high hydrogen substitution rate. The range of the maximum hydrogen substitution rate was determined under different loads (30%~90%) at 1800 rpm and, then, the effects of the EGR rate (0%~15%) and main injection timing (−8 °CA ATDC~0 °CA ATDC) on the engine performance under 90% high load were studied. The research results show that the larger the load, the smaller the maximum hydrogen substitution rate that can be added to the dual-fuel engine. Under each load, with the increase of the hydrogen substitution rate, the cylinder pressure and the peak heat release rate (HRR) increase, the equivalent brake-specific fuel consumption (BSFCequ) decreases, the thermal efficiency increases, the maximum thermal efficiency is 43.1%, the carbon dioxide (CO2) emission is effectively reduced by 35.2%, and the nitrogen oxide (NOx) emission decreases at medium and low loads, and the maximum increase rate is 20.1% at 90% load. Under high load, with the increase of EGR rate or the delay of main injection timing, the problem of NOx emission increases after hydrogen doping can be effectively solved. As the EGR rate rises from 0% to 15%, the maximum reduction of NOx is 63.1% and, with the delay of main injection timing from −8 °CA ATDC to 0 °CA ATDC, the maximum reduction of NOx is 44.5%.

Design Optimization of an Ethanol Heavy-Duty Engine Using Design of Experiments and Bayesian Optimization

Abstract Diesel-fueled engines still hold a large market share in the medium and heavy-duty transportation sector. However, the increase in fossil fuel prices and the strict emission regulations are leading engine manufacturers to seek cleaner alternatives without a compromise in performance. Alcohol-based fuels, such as ethanol, offer a promising alternative to diesel fuel in meeting regulatory demands. Ethanol provides cleaner combustion and lower levels of soot due to its chemical properties, in particular its lower level of carbon content. In addition, the stoichiometric operating conditions of alcohol fueled engines enable the mitigation of NOx emissions in aftertreatment stage. With the promise of retrofitting diesel engines to run on ethanol to reduce emissions, the thermal efficiency of these engines remains the primary optimization target. In order to find the optimal ethanol-fueled engine design that maximizes the thermal efficiency, a large design space needs to be investigated using engineering tools. In this study, previous research by the authors on optimizing the design of a single-cylinder ethanol-fueled engine was extended to explore the design space for a heavy-duty multicylinder engine configuration. A heavy-duty engine setup with multiple operating conditions at different engine speeds and loads was considered. A design optimization analysis was performed to identify the potential designs that maximize the indicated thermal efficiency in an ethanol-fueled compression ignition engine. First, a computational fluid dynamics (CFD) model of the engine was validated using experimental data for four drive cycle points. Using a design of experiments (DoE) approach and a parameterized piston bowl geometry, the model was then exercised to explore the relationship among geometric features of the piston bowl and spray targeting angle and indicated thermal efficiency across all tested operating conditions. After evaluating 165 candidate designs, a piston bowl geometry was identified that yielded an increase between 1.3% and 2.2% points in indicated thermal efficiency for all tested conditions, while satisfying the operational design constraints for peak pressure and maximum pressure rise rate. The increased performance was attributed to enhance mixing that led to the formation of a more homogeneous distribution of in-cylinder temperature and equivalence ratio, higher combustion temperatures, and shorter combustion duration. Finally, a Bayesian optimization (BOpt) analysis was employed to find the optimal piston bowl geometry with a fixed spray injector angle for one of the operating conditions. Using BOpt, a piston candidate was identified that resulted in a 1.9% point increase in thermal efficiency from the baseline design, yet only required 65% of the design samples investigated using the DoE approach.

Experimental study on thermoelectric effect pattern analysis and novel thermoelectric coupling model of BIPV facade system

Electrical and thermal energy are the primary forms of useful energy generated by building integrated photovoltaic façade (BIPV façade) systems, while their interaction during operation remains unclear. This study aims to analyze the energy generation patterns and quantify the impact of thermoelectric coupling in BIPV façade systems. Through long-term outdoor experiment conducted on an actual BIPV façade system, the underlying regularity of thermoelectric coupling was discovered by analyzing the electrical and thermal characteristics. Results showed that under same solar radiation, enlarged air channel spacing led to a 53.22% increase in air channel heat and a 12.27% increase in mean thermal efficiency. Additionally, the heat proportion increased by approximately 15%, while the electricity proportion decreased by 15%. Furthermore, the mathematical relationships of the thermoelectric association factors were determined to quantify the observed thermoelectric generation patterns. A novel thermoelectric coupling model was established and validated with errors below 6.21% for accurate estimation of thermoelectric performance under actual operating conditions. Results emphasized both thermal and electrical energy generation of BIPV façade, which offers a new perspective on the comprehensive utilization of thermoelectric association in BIPV façade design and building applications, opening avenues for enhanced energy efficiency in renewable energy systems.

Preliminary tests of a Diesel engine powered by diesel and hydrogen

This article discusses the possibilities of powering a commonly used diesel engine with renewable fuels. It analyses scientific studies that clearly indicate that the use of hydrogen is a potentially future-proof option due to its potential to reduce specific fuel consumption and improve performance and increase thermal efficiency. The research was carried out on a laboratory bench designed to test a diesel engine fueled by different fuels. A proprietary hydrogen injection system with dedicated control software was used. Hydrogen injection pressures of 1,5, 1,8, 2,0 MPa and hydrogen injector opening times of 2,5, 3,0, 3,5 ms, respectively, were set as control parameters. The rapidly varying engine operating parameters were recorded and the parameters calculated from them were analysed.

Effect of green fuel and green lubricant with metallic nanoparticles on emissions of HC, CO, NOx, and smoke for a compression ignition engine

The United Nations Sustainable Development Goals (SDGs) are imperative from the point of view of protecting the environment by employing sustainable options. Considerable research has been carried out in the transportation sector to meet this objective. Here, the influence is assessed of epoxidised gingelly oil methyl ester biolubricant with alumina (Al2O3) nanoparticles on the performance and emissions of a single cylinder 0.66-L capacity direct injection compression ignition engine driven by gingelly B20 biodiesel. Engine tests are carried out with gingelly B20 biodiesel as a fuel, and gingelly methyl ester (B100), epoxidised gingelly methyl ester (B100E), and epoxidised gingelly methyl ester (B100E) mixed with 0.5%, 1.0%, and 1.5% w/w alumina (Al2O3) nanoparticles as the lubricant combinations. The results are compared with baseline B20 biodiesel fuel-mineral lubricant operation. The findings indicate that brake thermal efficiency increases by 8.64% for epoxidised gingelly methyl ester (B100E) with 1.0% w/w alumina (Al2O3) nanoparticle biolubricant in comparison to baseline operation. Considerable reductions in emissions are detected; specifically, reductions of 52.4%, 22.0%, 20.0%, and 34.9%, respectively, are observed for CO, NOx, and HC concentrations and smoke opacity for the abovementioned combination as compared to baseline operation. The present work suggests that further research is merited on green fuel-green lubricant combinations. The findings of this study address the United Nations Sustainable Development Goals (SDGs) 7 and 13.

Multi-criteria assessment and optimization of a natural gas-fed solid oxide fuel cell combined heat and power system

Solid oxide fuel cell (SOFC) combined heat and power (CHP) system is a promising candidate for efficient power generation. Due to its complex dynamic characteristics, system performance is still unsatisfied when it operates in variable load conditions. In this study, five improved layouts of a natural gas-fed SOFC-CHP system are proposed using three-fluid heat exchangers innovatively. Performance of the system under different layouts is compared from both energy and exergy perspective and their feasibility in multi-load conditions is evaluated. Sensitivity analysis of four key parameters is conducted to clarify their influences and potential ways for efficiency improvements from both system and component level are explored under different load conditions. Results show that the system with direct combustion of anode off-gas has better adaptability to multi-load conditions. Exergy loss of the combustor always occupies the highest proposition among all the components, at least 30%. Because of the large thermal load and high outlet temperature of the cold fluid, thermal management of the reformer is crucial for the system operation. Changes of the reforming temperature and fuel utilization ratio significantly affect the system performance. As the load increasing, the electric efficiency decreases and the thermal efficiency increases, the total efficiency can always be more than 85% for the SOFC-CHP system.