Comparison Of Energy Performance Research Articles

Comparative Energy Performance Analysis of Solar Water Pumping Systems Across Diverse Climate Zones

The solar PV system-based water pumping plant is cost-effective in developing countries like India. This study compares remote solar water pumping systems, accounting various factors like site location, system size, and performance, in several climate-sensitive Indian regions. The PVsyst simulation software is used to design the standalone solar water pumping system. Data inputs are obtained from four different climatic locations in southern part of India. A comparative analysis is performed for the four regions based on the solar yield, performance ratio (PR), energy losses, and pump efficiency. The PVsyst simulation analysis shows that the overall pump efficiency ranges between 57% and 66%, and the performance ratio ranges between 51% and 69%. The outcome of the results is useful for making a policy decision about locating the best solar pumping station based on the climate conditions, particularly for remote villages.

Comparison of energy and environmental performance between warm and hot mix asphalt concrete production: A case study

The use of additives to produce warm bituminous mixtures in asphalt pavements gives the possibility to decrease temperatures with positive implications on energy consumption, and on emissions of greenhouse gases and airborne pollutants. This study investigates the changes in energy and environmental performance of an asphalt plant switching from hot to warm asphalt concrete production. A full-scale trial section was constructed in an Italian motorway with recycled bituminous mixtures containing SBS polymer modified bitumen. Reference hot mix asphalts (HMAs) mixed at 170 °C were compared with warm mix asphalts (WMAs) mixed at 130 °C with different chemical additives. Calculations and analysis were performed considering three production phases during which the production technologies (HMA and WMA) and the mixture types varied in temperatures, mixing duration, and quantity of virgin materials employed. Energy performance was calculated through values provided by the asphalt plant operator and thermodynamic equations. Emissions of CO2 were calculated based on energy consumption and emission factors reported in the literature for the Italian energy mix. Airborne pollutants were measured at the stack of the dryer drum. The results showed that for each mixture type, a reduction of 40 °C in the production temperature corresponds to 15% lower thermal energy values for the drying/heating of the aggregates, with consequent lower consumption of fuel oil. The drying/heating of aggregates for WMA lead to lower emissions of particulate matter, NOx, and VOCs compared to HMA.

Energy, economic, and environmental (3E) performance assessment, comparison, and analysis of airport cargo terminal microgrid system under the islanded and grid-connected modes

Microgrids, which can be grid-connected or isolated, may experience dependability issues as a result of intermittent renewable energy. The implementation of a hybrid renewable energy system (HRES) could alleviate this problem but is still a challenging task because of its interference, uncertain, and unpredictable nature. Currently, the absence of comprehensive assessment impedes large-scale applications. In this study, a novel 3E assessment method-based complete quantitative assessment is suggested and inventively integrated with a newly proposed triangle evaluation scheme. Loads of an airport cargo terminal, which are used to test the assessment approach, are classified into critical and non-critical categories according to their necessity. The microgrid system flexibility is considered by the trade-off of non-critical loads. Results show that the assessment method is more intuitive in quantifying the system's performance. The Levelized Cost of Energy (LCOE) in the islanded mode is lower than the current electricity price (from 0.5407 to 0.5439 CNY/kWh) and the annual carbon emission is reduced to one-third of that in the grid-connected mode. Its flexibility can effectively reduce dependence on backup power generation, where the daily peak shedding increases from 217.88 kW to 555.04 kW and daily hours without charging from 6.7 h to 8.9 h. The carbon emission decreases by 32 % considering the impacts of the system flexibility. Besides, the critical distance exists when the LCOE exceeds the current market electricity price.

Applicability of a dedicated outdoor air system assisted by isothermal dehumidification and evaporative cooling

A dedicated outdoor air system (DOAS) assisted by an isothermal dehumidifier and an indirect evaporative cooler is proposed, and its energy-saving potential is evaluated based on detailed simulations. In the proposed system, an isothermal dehumidifier accommodates the latent cooling load and an indirect evaporative cooler assumes a sensible cooling load. The energy performance of the proposed system was evaluated by comparing it with two conventional dedicated outdoor air systems: a DOAS with a desiccant wheel and a DOAS with a cooling coil. The results indicate that the proposed DOAS can accommodate sensible and latent cooling loads, but it consumes 10% more operating energy because of the low coefficient of performance (COP) (0.67) of the isothermal dehumidifier, despite the free cooling operation by the indirect evaporative cooler. For comparable energy performance, the proposed system requires the COP of the isothermal dehumidifier to be greater than 0.78, which is achieved through improvements in the membrane selectivity and vacuum pump (compression ratio and isentropic efficiency).

Comparative energy performance analysis of micro gas turbine and internal combustion engine in a cogeneration plant based on biomass gasification

With a view to replacing fossil fuels, biomass electricity generation worldwide has grown from 509 TWh in 2015 to 685 TWh in 2021 and an upward trend is expected for the next years. It is about dispatchable, low-emission power to complement generation from variable renewables. Although modern bioenergy is considered a stable and carbon-neutral source, there is a need to boost the efficiency of the Biomass-to-Energy (BtE) conversion technologies. Accordingly, in this modeling study, attention was drawn to biomass gasification for heat and power, with a special focus on the prime mover characterization for distributed generation. An internal combustion engine (ICE) and a micro gas turbine (mGT), having the same nominal capacity of about 240 kWel when fueled by natural gas (NG), were inserted into a two-way biomass gasification chain and hence fed by clean syngas deriving from a downdraft gasifier. Simulations of the main components of the thermal power plant (gasifier, syngas cleanup, power island) were validated against data available in the published literature and in technical sheets, for specific operating conditions. The next step was to evaluate the overall performance of the entire BtE chain in terms of electrical, thermal, and total efficiency, both at full and part load, in order to highlight the pros and cons of each generator, in a twofold perspective. The last goal was to simulate a load following strategy, for two typical cold and hot days. The results of the thermodynamic analysis indicate that ICE is better performing than mGT, in the simulated context where the power demand from the grid ranges from 80 kWel to 190 kWel, with an ambient temperature between 2 and 35 °C. ICE provides the best performance in CHP mode, with a total efficiency of 62–69%.

Comparison of building energy performance in three urban sites using field measurements and modelling in Kayseri, Turkiye

Despite the fact that the interrelationships between urban microclimates and energy demand have been recognised, there are not many processes that combine microclimatic boundary conditions to estimate energy consumption in parametric morphological investigations. Therefore, this paper will demonstrate a simple step-by-step methodology to incorporate the effect of urban microclimate on building cooling energy demand in semi-arid climatic areas. In this study, the combination of ENVI-met, Urban Weather Generator (UWG) and Rhino grasshopper are used to investigate the connection between microclimate and energy in the climatic environment of Kayseri. This coupling’s potential is investigated across compact high-rise, midrise and low-rise buildings, focusing on the cooling requirement on the hottest days. The comparative study shows how and to what extent urban geometry, building height in this case, contributes to modifying the magnitude of microclimate impact on building cooling performance.

The Nutritional Content of Meal Images in Free-Living Conditions-Automatic Assessment with goFOODTM.

A healthy diet can help to prevent or manage many important conditions and diseases, particularly obesity, malnutrition, and diabetes. Recent advancements in artificial intelligence and smartphone technologies have enabled applications to conduct automatic nutritional assessment from meal images, providing a convenient, efficient, and accurate method for continuous diet evaluation. We now extend the goFOODTM automatic system to perform food segmentation, recognition, volume, as well as calorie and macro-nutrient estimation from single images that are captured by a smartphone. In order to assess our system's performance, we conducted a feasibility study with 50 participants from Switzerland. We recorded their meals for one day and then dietitians carried out a 24 h recall. We retrospectively analysed the collected images to assess the nutritional content of the meals. By comparing our results with the dietitians' estimations, we demonstrated that the newly introduced system has comparable energy and macronutrient estimation performance with the previous method; however, it only requires a single image instead of two. The system can be applied in a real-life scenarios, and it can be easily used to assess dietary intake. This system could help individuals gain a better understanding of their dietary consumption. Additionally, it could serve as a valuable resource for dietitians, and could contribute to nutritional research.

The thermal and energy performance comparison of extruded polystyrene foam insulation for an apartment building in different climate zones,Egypt

The thermal and energy performance comparison of extruded polystyrene foam insulation for an apartment building in different climate zones,Egypt

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.

Evaluating the sustainable features of vernacular architecture in hot-arid regions: field surveys and analysis in two vernacular houses in Al Batinah region (Oman)

ABSTRACT The necessity to derive sustainable building solutions from the local vernacular architecture is being increasingly asserted in the global debate about the immense energy consumption, natural resources depletion, and high levels of Green House Emissions (GHG). Paradoxically, a limited number of research has addressed this issue in the arid hot regions and much less in the Arabian Peninsula. As a contribution to this debate, the present paper evaluates the sustainable features present in the Omani vernacular houses and their efficacy in terms of thermal comfort and energy performance. A Methodology that combines on-site measurements with modelling simulations, using DesignBuilder software, was applied to achieve the three objectives assigned to this study: (a) Characterization of Vernacular Architecture in Oman and its bioclimatic features, (b) Evaluation of the thermal and energy performance of a selected vernacular house. (c) A comparison of thermal and energy performance between a vernacular dwelling and a contemporary Omani house. The numerical simulation confirmed that the vernacular construction system provides enhanced thermal performance when compared to its modern counterpart. It has also been showed that the house with a vernacular construction system requires twice less cooling energy than its modern counterpart.

Energy and Environmental Performance Comparison of Heat Pump Systems Working with Alternative Refrigerants

The European Parliament has imposed to reduce by 2030 whole HFC emissions by at least two-thirds with respect to 2014 levels. With the aim of contributing to determine the energy and environmental advantages of refrigerants alternative to R-410A, this paper reports the results of a numerical study focused on an HVAC system coupled to a residential building and based on a reversible electric heat pump. In particular, two heat pump typologies are considered: an air-source and a ground-source heat pump, both operating with the two refrigerants R-410A and R-454B. The environmental performance of the studied system is assessed by means of the TEWI (total equivalent warming impact) index. The adoption of R-454B involves a slight decrease (2–3%) in the overall annual energy performance of the system with respect to the use of R-410A. On the other hand, the working fluid R-454B guarantees a marked decrease in the TEWI indicator. Indeed, considering the current Italian emission factor of electricity taken from the grid, the total emissions over the entire heat pump operating life drop by about 25% and can decrease by up to 89% in perspective, following the current reduction trend of the emission factor.

Energy Performance Comparison of a Chiller Plant Using the Conventional Staging and the Co-Design Approach in the Early Design Phase of Hotel Buildings

As part of the design process of a chiller plant, one of the final stages is the energy testing of the system in relation to future operating conditions. Recent studies have suggested establishing robust solutions, but a conservative approach still prevails at this stage. However, the results of some recent studies suggest the application of a new co-design (control–design) approach. The present research involves a comparative analysis between the use of conventional staging and the co-design approach in the design phase of a chiller plant. This paper analyzes the energy consumption estimations of six different chiller plant combinations for a Cuban hotel. For the conservative approach using on/off traditional staging, the results suggest that the best option would be the adoption of a chiller plant featuring a symmetrical configuration. However, the outcomes related to the co-design approach suggest that the best option would be an asymmetrical configuration. The energy savings results were equal to 24.8% and the resulting coefficient of performance (COP) was 59.7% greater than that of the symmetrical configuration. This research lays firm foundations for the correct choice and design of a suitable chiller plant configuration for a selected hotel, allowing for significant energy savings in the tourism sector.

수용액 원심분사 기술이 적용된 액체식 제습 시스템의 제습 및 에너지 성능에 대한 실험적 연구

The main objective of this study was to analyze the dehumidification performance of a centrifugal atomization-based liquid desiccant (LD) dehumidification system and compare energy performance. Dehumidification rate and effectiveness were evaluated to determine dehumidification performance. A parametric study was performed experimentally according to five variables: air temperature, air humidity ratio, solution temperature, solution concentration, and liquid-to-gas ratio. Cooling load was also compared with a packed-bed-based LD dehumidification system via experiment results and simulations. Results indicated that the dehumidification performance was improved at low solution temperature and high solution concentration. The dehumidification rate was also higher in hot and humid air than in a mild air condition. As liquid-to-gas ratio increased, dehumidification effectiveness also increased while dehumidification rate decreased. Finally, the proposed centrifugal atomization-based LD system could achieve the same dehumidification performance at a lower liquid-to-gas ratio than packed-bed-based LD system while saving 72% system cooling load.

Benchmarking high performance HVAC Rule-Based controls with advanced intelligent Controllers: A case study in a Multi-Zone system in Modelica

The design, commissioning, and retrofit of heating, ventilation, and air-conditioning (HVAC) control systems are crucially important for energy efficiency. However, designers and control contractors adopt ad-hoc control sequences based on diffused and fragmented information; therefore, most of the existing control sequences are diverse and sub-optimal. ASHRAE Guideline 36 (GDL36), High-performance Sequences of Operation (SOO) for HVAC Systems, was thus developed to provide standardized and high-performance rule-based HVAC control sequences with the main focus on maximizing energy efficiency. However, only limited studies verify the performance of these high-performance rules-based control and most of these studies focus on the single-zone systems. In this Modelica-based simulation study, the high-performance rule-based control sequences from GDL36 were compared to the state-of-the-art intelligent controllers (i.e., optimization-based controller (OBC) and deep reinforcement-learning-based controller (DRLC)) in terms of the energy efficiency and thermal comfort. The performance evaluation was conducted in a medium-sized office building with a multi-zone Variable Air Volume (VAV) cooling system. The OBC and DRLC replaced the GDL36 airside supervisory level control loops. In other words, the optimal supply air temperature (SAT) and static differential pressure (DP) setpoints were determined by the optimization problems in OBC and trained control policy by DRLC. The OBC and DRLC were formulated to minimize the HVAC energy consumption and zone air temperature violation. The OBCs with different control intervals and DRLCs with different hyperparameters in the Proximal Policy Optimization (PPO) algorithm were exploited and fine-tuned. The simulation results show that the GDL36 has a comparable energy performance (within a 3% deviation) with DRLC in the cases with high or mild cooling loads. It also has a comparable energy performance (within a 3% deviation) with OBC in the case of a high cooling load. However, the case with GDL36 consumed 7% more energy in the testing shoulder period. For the thermal comfort metric, the GDL36 has slightly more zone air temperature violations in all testing scenarios compared to the two intelligent controllers. From this case study, we can conclude that the GDL36 has demonstrated its comparable performance in terms of energy efficiency and thermal comfort with the two intelligent controllers. The GDL36 airside SOO is good enough considering the complexity and tuning efforts of the intelligent controllers.

Comparison of Short and Long-Term Energy Performance and Decarbonization Potentials between Cogeneration and GSHP Systems under MARKAL Scenarios

In response to the call for global carbon peaking and neutrality, this study mainly focuses on the comparison of energy-related carbon emissions and the performance of two promising heating, ventilation, and air-conditioning technologies (a ground source heat pump (GSHP) and cogeneration systems) over both short (2021–2030) and long (2031–2050) periods, considering the UK decarbonization plans. The simulation model of the building with the GSHP system is validated by the actual building heating energy data in 2020 and 2021, with yearly deviations of only 0.4–0.5%. The results show that the cogeneration system performed better than the GSHP system in a scenario when there was no electricity decarbonization plan in the future. However, under all of the MARKet ALlocation (MARKAL) scenarios, the GSHP system performed much better than the cogeneration system in terms of carbon reduction in both periods, which can achieve 47.8–84.4% and maximum 97.5% carbon emission savings in short and long-term periods, respectively, compared with the cogeneration system. Due to the truth that electricity decarbonization plans will be optimized and executed in the future, the GSHP system is more promising and recommended compared with cogeneration system in both short- and long-term periods in terms of only decarbonization potentials (e.g., reducing carbon emission and achieving carbon-related environmental protection).

The role of Primary Energy Factors (PEF) for electricity in the evaluation and comparison of building energy performance: An investigation on European nZEBs according to EN 17423:2020

• Primary energy factors (PEF) for electricity are temporally and geographically variable • The EN 17423: 2020 standard proposes a unified method for calculating PEFs • Building performance is significantly affected by the impact of PEFs. • The adoption of shared PEF allows an adequate comparison between buildings • PEF assessment can support national energy policies in the energy transition Evaluating the energy performance of buildings is a fundamental aspect for quantifying the impact of national energy policies supporting energy transition and sustainable development of countries. However, evaluations carried out on final energy consumption risk leading to approximate solutions that do not take into account the generation, transmission and distribution efficiency of energy systems. Furthermore, it is increasingly difficult to compare similar buildings that belong to different geographical contexts. To overcome these problems, a common solution, that is adopted at European and international level, is the use of the concept of primary energy, and the relative primary energy factor (PEF). The current assessment of primary energy for the performance of European buildings is governed by individual national laws, which are often out-to-date and not representative of current national energy systems. In this work, the recent EN 17423:2020 standard was adopted to apply a harmonized methodology in the evaluation of PEF for different European countries, considering the electricity energy vector. The results demonstrated first an important variation in the primary energy factor over the last 20 years, with decreases from -7% (in France) to -32% (in Denmark). Using this methodology, the primary energy needs of 37 European representatives nearly Zero Energy Buildings (nZEBs), located in 11 different member countries, were assessed. For the first time in literature, it was possible to compare European buildings energy performance following a standardized assessment procedure. The implications of this work represent a starting point for comparisons on the European building stock, also indicating the need for an update of national regulations regarding the assessments of the energy performance of buildings.

Numerical comparison of thermal energy performance between spouted, fluidized and fixed beds using supercritical CO2 as fluidizing agent

The different thermal energy performance between spouted, fluidized, and fixed beds when using supercritical CO2 as a fluidizing agent was numerically investigated by employing a combined approach of Computational Fluid Dynamics (CFD) and Coarse-Grained Particle (CGP) methods. The model was first validated against experimental data available in the literature, confirming that the simulated particle velocity and temperature agreed well with the experimental measurements. The numerical results reveal that for the spouted bed, gas velocity, gas temperature, and convective heat transfer were higher in the spout region. Hence, most heat was transported directly from the inlet to the outlet of this system. For the fluidized bed, the particles near the gas inlet were quickly heated up at first, and a uniform temperature distribution was achieved in the whole bed during the later stages of the process. Concerning the fixed bed, its behavior is well-known with three temperature zones differentiated, which are a hot region, a cold zone, and the intermediate thermocline. Besides, numerical simulations allow further analysis in detail of the different heat transfer mechanisms in the configurations tested. Convection is the dominant mechanism in all cases. Conduction is noticeable in the fixed bed regime compared to the spouted or fluidized regimes, but even in this case, it is still an order of magnitude lower than the convection mechanism. Finally, thermal energy and exergy were also analyzed for the three beds.

Comparative energy performance evaluation and uncertainty analysis of two building archetype development methodologies: A case study of high-rise residential buildings in Qatar

Building Archetypes (BAs) are often used in modeling urban-scale building energy consumption profiles to represent the energy consumption behavior of typical buildings within the modeled urban environment. One current approach to the development of BAs involves the creation of Building Energy Models (BEMs) using surveyed data coupled with codes, standards, or engineering experience. Another approach is the modification of existing standardized BEMs using available data to produce a suitable BA for the representation of the building stock. The adoption of either of these methods has been treated as an axiom or a step that did not need much consideration. However, the results produced by BEMs created according to different methodologies present several differences. The discrepancy in the produced results is shown not only in the results of the BEMs developed according to different methodologies but also in the degree to which these results vary when changing input values. Limited studies analyzed the sensitivity of these models to uncertain inputs, even though it is essential for the development of BA libraries. This paper comparatively investigates the Region-Specific (RS) and Department of Energy (DOE)-based BEM creation methods for BA library development. The models are developed by following the two methodologies, and their predictions are compared to the metered data from a high-rise residential building in the Marina district of Lusail City, Qatar. A Global Sensitivity Analysis (GSA) method is used to identify the most influential parameters contributing to the energy consumption variation of these models. Further, a parametric simulation campaign is conducted by varying the inputs determined earlier to quantify the BEMs’ output variability. According to the results, the baseline RS BEM and DOE BEM yield an Energy Use Intensity (EUI) of 211.03 kWh/m2 and 137.9 kWh/m2, respectively. The deviation of these values from the metered EUI of 185,37 kWh/m2 indicates that the RS BEM development methodology is preferable to the DOE BEM for the BA development. Based on the GSA results, regardless of the BEM development methodology used, the most important parameters contributing to output variation are the Cooling Setpoint, the Outdoor Air Requirements, the Equipment Power Density, and the Lighting Power Density. Further, the RS BEM’s parametric simulations produce a mean cooling EUI of 324.83 kWh/m2, closer to the literature benchmarks than the mean cooling EUI of DOE BEM, 341.62 kWh/m2. The results obtained from the baseline model and the uncertainty analysis support the conclusion that a Region-Specific Model developed from the ground up serves to better represent high-rise residential buildings in regions with extreme climate conditions. The impact this work achieves is providing decision-making support for urban scale building energy modelers for future building stock representation efforts in such areas while also providing an expected uncertainty range for the developed high-rise residential archetypes.

Investigating the Energy-Efficient Structures Using Building Energy Performance Simulations: A Case Study

The use of energy efficient structures in the local construction industry assists in promoting green building concepts, leading to economical and eco-friendly solutions for self-sustained structures. The main aim of this study was to examine and compare the energy performance of various local buildings. Detailed 3D building models (house, office, and warehouse buildings) were constructed and investigated for their cost and energy savings using building energy simulation tools (green building studio and insight). Moreover, the effects of various building materials for walls, window panels, and roof construction were explored, and a life-cycle cost analysis was performed. It was observed that the effect of the window-to-wall ratio was less severe in term of energy use in office buildings compared to normal houses due to the larger amount of space available for air circulation. Furthermore, the most efficient location for windows was found to be at the middle of the wall in comparison with the top and bottom positions. The effect of the orientation mainly depended on the symmetry of the building. More symmetric buildings, i.e., tested warehouse buildings (rectangular structure), showed an energy use difference of around 7 MJ/m2/year for a 360° orientation change. Tested house buildings exhibited an energy use difference of up to 25 MJ/m2/year. Three-pane glass windows also showed major improvements, and the total energy consumption for houses was reduced to 14%. Furthermore, wood walls showed comparable energy performance with brick walls without the use of insulation. According to US-LEED guidelines, the tested house, office, and warehouse buildings achieved 79, 89, and 88 points, respectively. The cost recovery period for house, office, and warehouse buildings was estimated to 54, 13, and 14 years, respectively, including running and maintenance costs. It can be argued that the Insight and Green Building Studio packages can assist construction stakeholders to determine the energy efficiency of the modeled building as well as to help in the selection of materials for optimized and improved design.

Energy and economic performance comparison of heat pump and power cycle in low grade waste heat recovery

For the sake of making an appropriate choice for the reuse of low grade waste heat, the mechanical heat pump, steam turbine (ST), and organic Rankine cycle (ORC) are modeled by Aspen Plus. The working conditions of 100–150 °C waste heat temperatures, as well as 10–30 °C heat pump temperature lifts are simulated and calculated. The price ratio of electricity to heat is introduced as an important economic variable. The energy and economic performance of the three technologies in low grade waste heat recovery are compared and analyzed based on the exergy efficiency and annual revenue. The results indicate that in terms of the exergy efficiency, the mechanical heat pump is always the best choice. From the perspective of the annual revenue, the mechanical heat pump is the best choice in most cases. The chance that the annual revenue of the ORC and ST is greater than that of the mechanical heat pump arises only when the price ratio of electricity to heat is greater than 5. As for the payback period, all the cycles can meet the requirements of enterprises. A guide of the selection of waste heat recovery technology based on economics is drawn.