Waste Heat Recovery Applications Research Articles

Exergoeconomic evaluation of an organic Rankine cycle integrated with a compression refrigeration to select the best working fluid for waste heat recovery application: a case study of Isfahan, Iran

Exergoeconomic evaluation of an organic Rankine cycle integrated with a compression refrigeration to select the best working fluid for waste heat recovery application: a case study of Isfahan, Iran

Dynamic performance analysis of transcritical power cycle with preheater and regenerator using CO2-based binary zeotropic mixtures

The CO2 transcritical Rankine cycle is considered as an ideal solution in the application of waste heat recovery due to its safety, environmental friendliness and compactness characteristics. In this work, for the heat recovery from internal combustion engine, a dynamic model of an improved CO2 transcritical Rankine cycle system containing both a preheater and regenerator with CO2-based binary zeotropic mixtures as working fluid is developed. The performance of CO2 transcritical power cycle with preheater and regenerator was compared and analyzed for mixture working fluids with different proportions under the disturbance of heat source conditions and system input parameters, which can provide references for system control strategy to ensure efficient and stable operating conditions when selecting control variables. The results show that there is a certain pump speed to obtain the optimal value of the net output work and thermal efficiency of the system. And the net output power and thermal efficiency of system with CO2-based binary zeotropic mixtures at optimum point are higher 6. 34 kW and 2.19% respectively than pure CO2 as working fluid by adjusting pump speed.

Investigations of microstructures and thermoelectric properties of TiNiSn half-Heusler compounds with micro- and nano-scale copper additions

The TiNiSn-based half-Heusler compounds have been considered as a promising thermoelectric material system for waste heat recovery applications. There have been numerous studies dedicated to improving its intrinsic low thermoelectric performance, and one strategy is to incorporate certain types of metal dopants into the host materials. Only a few research works have been focused on the effects of the dimensions of metal particles on the thermoelectric properties of materials. In this study, we investigate the roles of micro- (M) and nano-scale (N) Cu powders in affecting the microstructures and thermoelectric properties of TiNiCuxSn (x = 0−0.1) compounds. Owing to the ease of oxidation of Cu nanoparticles and the tedious preparation procedure, TiNiCux, NSn shows lower carrier concentration and electrical conductivity compared to the TiNiCux, MSn with the same nominal Cu content. The high-temperature Seebeck coefficient of TiNiCux, NSn gradually deteriorates as the temperature rises, partly due to the impurities-induced bandgap narrowing effect. The maximum power factor achieved for TiNiCux, NSn is about 20.2% lower than that for TiNiCux, MSn. Even though the reduced contribution of electronic component leads to a lower total thermal conductivity at low temperatures, the highest zT obtained in TiNiCux, NSn is markedly lower than that in the corresponding TiNiCux, MSn. These findings highlight the importance of investigating the dimensions of metal dopants in studies of the thermoelectric properties of materials.

Effects of Installing Different Types of Cooling Fins on the Cold Side of a Thermoelectric Power Generation Device on the Thermal Efficiency and Exergy Efficiency of Power Cable Surface Waste Heat Recovery.

This study investigates the thermal efficiency and exergy efficiency of a thermoelectric power generation device for recovering power cable surface waste heat. Numerical simulations are conducted to analyze the impact of different types of cooling fins on the system's performance. The results demonstrate that the installation of cooling fins improves heat transfer efficiency and enhances the thermoelectric power generation device's output power. Among the various fin designs, the system equipped with cooling fins with 17 teeth exhibits the highest performance. These findings highlight the importance of fin design in optimizing the system's thermal efficiency and exergy efficiency. This study provides valuable insights for the development and improvement of thermoelectric power generation systems for power cable surface waste heat recovery applications.

Enhancing sustainable energy conversion: Comparative study of superheated and recuperative ORC systems for waste heat recovery and geothermal applications, with focus on 4E performance

This study investigates the 4E performance of small-scale (<100 kW), low-temperature (<179 °C) Organic Rankine Cycle (ORC) technology, comparing two distinct configurations using different working fluids and heat sources. The work utilizes experimental methods to analyse the efficiency of the ORC systems, focusing on variables such as evaporation temperature and pressure drop across the heat exchanger. Various working fluids and heat sources are tested to evaluate their impact on performance using CoolProp libraries.The results reveal that the ideal evaporation temperature for maximizing overall performance and efficiency is between 140 and 150 °C. Higher pressure drop across the heat exchanger improves heat transfer, thermal efficiency, and power output, but increases pumping requirements and reduces overall effectiveness. Among the tested heat sources, the Dynalene SF exhibits the best performance, followed by therminol T72, T66, geothermal water, and Paratherm HE. The most suitable working fluids for commercial ORC units are R245fa and hexamethyldisiloxane (MM), providing excellent thermodynamic properties and low environmental impact. Comparatively, the superheated ORC system using R245fa outperforms the MM, achieving higher net efficiency (7.29%), greater network generation (20.29%), and improved exergy efficiency (20.54%). The economic viability of the recuperative system is evident from the Levelized Cost of Electricity (LCOE) range of 12.4–14.5 (cents/kWh), with an average Total Installed Cost (TIC) of 354.5 k$. These results showcase the system's competitiveness in providing cost-effective electricity generation, reaffirming its potential as a financially viable option for sustainable energy solutions.The objective is to explore the use of Organic Rankine Cycle (ORC) technology as an alternative to steam Rankine cycle for low-power and lower-temperature applications. Specifically, the study focuses on ORC systems with external heat sources, including geothermal, solid fuels and waste heat recovery (WHR).The novelty of this article lies in its updated analysis of the techno-economic-environmental feasibility of ORC systems for different applications, which goes beyond previous studies. It provides a systematic evaluation and comparison specifically tailored to small-scale and low-temperature operating conditions. The aim is to promote the integration of these two systems in various sectors, particularly for countries undergoing an energy transition. This emphasis on the technical aspects and the specific focus on small-scale and low-temperature conditions make this study unique and valuable in advancing the understanding and application of ORC technology.

Characterization by differential scanning calorimetry of thermal storage properties of organic PCMs with operating temperature of 150 °C

The involvement of Phase Change Materials (PCMs) in energy storage systems leads to more sustainable and efficient use of energy. Medium operating temperature (melting point 100–400 °C) find various applications in industrial waste heat recovery and hybrid compressed air - thermal energy storage systems. However, there is still a lack of detailed knowledge in terms of their thermal storage properties that hinders them from being more integrated in industry. In this study, thermal properties such as melting point, enthalpy and heat capacity of three medium temperature PCMs were characterized using Differential Scanning Calorimetry (DSC). The enthalpy-temperature graph for each PCM is presented that contains key information on sensible and latent heat contribution in the total energy storage. The selected organic PCMs are adipic acid with two different purities 99%, 99.5%, and its chemical equivalent PureTemp151® with a melting point of (150.5 ± 0.5 °C) and a latent heat of (230 ± 10 J/g). Furthermore, the effect of heating rate and sample mass in DSC procedures on transition temperatures and enthalpy were evaluated. Finally, thermal performance of PCMs was quantified through 150 cycles of melting and solidification. The tested PCMs show a significant storage capacity and good thermal stability with less than 10 % enthalpy loss.

Comparative assessment of the various split flow supercritical CO2 Brayton cycles for Marine gas turbine waste heat recovery

Supercritical CO2 Brayton cycle (sCO2 BC) can become easily utilized in marine gas turbine waste heat recovery applications due to their high efficiency, compact size, and low-cost advantages. In this study, the performance of the three different split flow sCO2 BCs, including turbine split flow-1 (TSF-1), turbine split flow-2 (TSF-2), and turbine split-3 (TSF-3), for the recovery of marine gas turbine waste heat is compared. The Engineering Equation Solver (EES) application is used to compare the three different split flow sCO2 BCs' performances. Moreover, to investigate the influence of important thermodynamic parameters on cycle performance, a parametric analysis is carried out. The effect of variable exhaust gas temperature, turbine input pressure, and compressor inlet pressure on net power, the energy efficiency of the system, system's exergy efficiency, and exergy destruction are examined. The results suggest that the energy efficiencies of the TSF-1 sCO2 BC, the TSF-2 sCO2 BC, and the TSF-3 sCO2 BC are calculated by 28.71%, 34.5%, and 29.42%, respectively. The TSF-2 sCO2 BC has more advantages in efficiency among all the cycle layouts while the TSF-3 sCO2 BC layout has better performance in the net power. In addition, the TSF-3 sCO2 BC has the highest exergy destruction at 99.71 kW, followed by the TSF-1 sCO2 BC at 91.83 kW and the TSF-2 sCO2 BC at 41.75 kW. It has been determined that the cycle's net power increases with rising exhaust gas temperature and turbine input pressure and decreases with compressor input pressure. Exhaust gas temperature and turbine inlet pressure have a positive effect on the performance of all split flow sCO2 BCs.

Dynamic behaviour of automobile thermoelectric waste heat recovery under different driving cycles

Different types of vehicles often run in different driving cycles, resulting in different dynamic behaviours of the automobile thermoelectric generator. The dynamic performance of a simplified automobile thermoelectric generator under different driving cycles, including HWFET, NEDC, WLTP, and CLTC, is evaluated to guide the application of automobile thermoelectric waste heat recovery by a hybrid transient CFD-TE model. The model is experimentally validated with an average output error of 10.92%, mainly caused by the instrument error. The findings indicate that the response of the dynamic output power of the automobile thermoelectric generator exhibits smoother fluctuations compared to the exhaust temperature, and also displays hysteresis in its response, while the dynamic conversion efficiency experiences sharp fluctuations. The behaviour of the automobile thermoelectric generator in dynamic situations is not entirely proportional to the vehicle speed but is instead dependent on changes in vehicle speed, more specifically, the change of exhaust heat. By comparing the steady and dynamic results, it is found that the steady-state model overestimates the output power but may underestimate the conversion efficiency. The automobile thermoelectric generator is more suitable for vehicles with frequent speed changes, such as passenger cars on urban and suburban roads, to enhance the dynamic output performance.

The Investigation of Two-Phase Expansion Performance with Indicator Diagram in a Twin-Screw Expander

Volumetric expanders are proven to be more suitable for small-scale waste heat recovery applications because of their simplicity, reliability, lower rotational speed and lower cost. Unlike turbines, volumetric expanders can work in the two-phase fluid state, which broadens their application fields. To investigate the two-phase performance of volumetric expanders, a specific twin-screw expander was chosen and modeled. The leakage loss and the suction pressure loss were primary concerns in this research. The two-phase expansion process in the expander is presented in detail using the developed mathematical model with an indicator diagram. The influence of several factors, including inlet vapor quality, rotational speed and intake pressure, are investigated. The influence mechanism of the vapor phase and the liquid phase on expander performance is clarified. In brief, this paper presents an illustrative understanding of the two-phase expansion process in twin-screw expanders.

Mathematical model establishment and optimum design of a novel cesium thermionic–thermoelectric hybrid generator

Static power sources, such as thermionic energy converters (TEC), thermoelectric generators (TEG), thermophotovoltaic converters (TPV), and alkali metal thermal to electric converters (AMTEC), have enormous potential application in aerospace, military, electronic devices, and low-grade waste heat recovery and utilization. Aiming to further improve the power output and conversion efficiency, any two of them can be cascaded according to the difference in operating temperature. In this study, a novel mathematical model of the static hybrid power generator composed of a cesium thermionic energy converter (CTEC) and a TEG was proposed. The model considered the irreversible heat loss and the additional energy barrier of the CTEC module, and the Thomson effect of the TEG module, synchronously. To obtain the temperature distribution of CTEC and TEG modules, energy balance equations were determined by nonequilibrium thermodynamic analysis. Then, the effects of the output voltage and anode work function of the CTEC, the heat source temperature, and the electric current of the TEG on the output performance were investigated systematically by means of MATLAB. The results indicate that the maximum efficiency of the hybrid generator reaches 26.82% at heat source and heat sink temperatures of 1800 K and 300 K, respectively, which is significantly higher than that of the individual CTEC module (21.28%). This reveals that the waste heat released by the CTEC is utilized effectively in the TEG module, and the increased heat source temperature will further improve the hybrid generator’s power output and efficiency. The output power and efficiency are obviously improved by reducing the anode work function. When ϕC = 1.0 eV, i = 0.005, the power reaches a maximum of 21.61 W at 0.37 V, and the efficiency reaches a maximum of 25.90% at 0.55 V. Moreover, the curve of the output power as a function of conversion efficiency could be used to determine the optimal operating region of the hybrid generator, i,e., Pη < P < Pmax, ηP < η < ηmax, thereby obtaining the thresholds of the hybrid system parameters, i.e., VP < V < Vη, T1,P < T1 < T1,η, T2,P > T2 > T2,η, T3,P > T3 > T3,η and TCs,P > TCs > TCs,η. This study provides a reference for the optimal design and application of a CTEC–TEG hybrid generator in the future.

THERMODYNAMIC ANALYSIS OF RECUPERATIVE AND REHEAT BASED ON ORGANIC RANKINE CYCLE FOR HIGH-TEMPERATURE WASTE HEAT RECOVERY

Heat recovery from available waste heat is an essential method in renewable energy processes due to the ability to generate electricity by using Organic Rankine Cycles (ORC). The process model is developed with the Cycle Tempo software. Fluid properties were analyzed with Reference Fluid Properties (REFPROP) software. This research presents a thermodynamic comparison of the Basic Organic Rankine Cycle (BORC) and Recuperative Organic Rankine Cycle (RORC) for waste heat recovery applications using pure refrigerants R-141b, R-245fa, R-123, and R-21. By performing simulations for heat source high-temperatures ranging from 160 to 200 °C. The comparison between BORC and RORC performance parameters and refrigerant properties was evaluated on the heat source temperature. Research shows that RORC produces higher thermal efficiency but has lower irreversibility than BORC. RORC has a maximum thermal efficiency of 12.67%, and BORC has a thermal efficiency of 11.49% for refrigerant R-141b at a flue gas temperature of 160 °C. The thermal efficiency of the ORC increases as the temperature of the heat source increases.

Comparative Assessment of sCO2 Cycles, Optimal ORC, and Thermoelectric Generators for Exhaust Waste Heat Recovery Applications from Heavy-Duty Diesel Engines

This study aimed to investigate the potential of supercritical carbon dioxide (sCO2), organic Rankine cycle (ORC), and thermoelectric generator (TEG) systems for application in automotive exhaust waste heat recovery (WHR) applications. More specifically, this paper focuses on heavy-duty diesel engines applications such as marine, trucks, and locomotives. The results of the simulations show that sCO2 systems are capable of recovering the highest amount of power from exhaust gases, followed by ORC systems. The sCO2 system recovered 19.5 kW at the point of maximum brake power and 10.1 kW at the point of maximum torque. Similarly, the ORC system recovered 14.7 kW at the point of maximum brake power and 7.9 kW at the point of maximum torque. Furthermore, at a point of low power and torque, the sCO2 system recovered 4.2 kW of power and the ORC system recovered 3.3 kW. The TEG system produced significantly less power (533 W at maximum brake power, 126 W at maximum torque, and 7 W at low power and torque) at all three points of interest due to the low system efficiency in comparison to sCO2 and ORC systems. From the results, it can be concluded that sCO2 and ORC systems have the biggest potential impact in exhaust WHR applications provided the availability of heat and that their level of complexity does not become prohibitive.

Enhanced zT due to non-stoichiometric induced defects for bismuth telluride thermoelectric materials

Thermoelectric materials have potential applications in energy conversion and waste heat recovery. Thermoelectric materials with non-stoichiometric composition may exhibit improved thermoelectric properties compared to the stoichiometric composition material. Bi2Te3 is one of the best-known thermoelectric materials having optimum performance near room temperature. In the present study, non-stoichiometric bismuth telluride (Bi2±x Te3), x = (0, 0.01, 0.02, 0.03), was synthesized using the co-precipitate method to create imperfections and strains in the crystal structure of the material. The crystal structure of the synthesized bismuth telluride revealed significant changes in the c direction when examined using X-ray diffraction (XRD). Scanning electron microscopy (SEM) revealed the formation of micro-particles. Energy dispersive spectroscopy (EDX) also confirmed the non-stoichiometric elemental composition of Bi and Te rich bismuth telluride. Thermogravimetric analysis (TGA) was performed in a non-inert environment, and an oxidation temperature of 685 ​K was recorded in non-stoichiometric samples. The post-oxidation of stoichiometric and non-stoichiometric Bi Rich and Te Rich bismuth tellurides was also confirmed by XRD and TGA comparison. The thermal conductivity was reduced by the imperfections and defects for all non-stoichiometric compositions, and a zT value of 0.54 at 420 ​K was obtained in the Tellurium Rich bismuth telluride, which is about a 12% improvement compared to the pure sample.

GA−BP Prediction Model for Automobile Exhaust Waste Heat Recovery Using Thermoelectric Generator

Thermoelectric generator (TEG) has important applications in automotive exhaust waste heat recovery. The Back propagation neural network (BP) can predict the electrical generating performance of TEG efficiently and accurately due to its advantage of being good at handing nonlinear data. However, BP algorithm is easy to fall into local optimum, and its training data usually have deviation since the data are obtained through the simulation software. Both of the problems will reduce the prediction accuracy. In order to further improve the prediction accuracy of BP algorithm, we use the genetic algorithm (GA) to optimize BP neural network by selection, crossover, and mutation operation. Meanwhile, we create a TEG for the heat waste recovery of automotive exhaust and test 84 groups of experimental data set to train the GA−BP prediction model to avoid the deviation caused by the simulation software. The results show that the prediction accuracy of the GA−BP model is better than that of the BP model. For the predicted values of output power and output voltage, the mean absolute percentage error (MAPE) increased to 2.83% and 2.28%, respectively, and the mean square error (MSE) is much smaller than the value before optimization, and the correlation coefficient (R2) of the network model is greater than 0.99.

Design, computational and experimental investigation of a small-scale turbopump for organic Rankine cycle systems

The hydraulic design, computational analysis, and experimental investigations of a high-speed small-scale turbopump for mobile waste heat recovery applications based on organic Rankine cycle systems are presented in this paper. Such applications demand high-pressure rise, lightweight, and compact pumping systems with simple construction. The investigated turbopump features an unshrouded 37.75 mm tip diameter single-stage centrifugal pump equipped with eight radial blades, eight splitters blades, and a rectangular axisymmetric volute. The pump should deliver 0.28 kg/s of mass flow rate with a pressure rise of 20 bar at a designed rotational speed of 25,000 rpm. Due to uncertainties observed in employing state-of-the-art 1-d methods that are valid for much larger machines, computational fluid dynamics is utilized to obtain a design meeting the specifications. The pump’s performance is evaluated experimentally at different rotational speeds, mass flow rates, and impeller tip clearances. The excellent agreement between experimental data and predictions from computational fluid dynamics validates the design methodology and computational results. The turbopump’s characteristics are then utilized to estimate the possible performance improvement of a target organic Rankine cycle using the novel turbopump instead of a commercial multi-stage centrifugal pump. The comparison suggests that the novel turbopump increases the efficiency of the target organic Rankine cycle by 0.3 % points and decreases its back-work ratio by nearly 50 %. The novel turbopump is approximately ten times more compact compared to commercial systems.

Macroencapsulated carbonate eutectic salt phase change material with high durability for high temperature heat storage

Carbonate eutectic salt is a kind of promising phase change material (PCM) for high temperature thermal storage application, which unfortunately constrained by its significant corrosiveness and low thermal conductivity. The encapsulation of salt PCM with stable inorganic shell to make capsules of millimeter to centimeter size can solve these problems, which is unfortunately technologically difficult to be prepared. In this work, a double shell strategy was proposed to coat the salt macrospheres with inner expanded graphite (EG) layer and outer ceramic kaolin layer. All raw materials were powders, which were shaped to spheres and capsules with the help of organic binder, pressed by isostatic pressing and finally sintered at high temperature for capsule formation. In a comparative case, the single kaolin shell coated capsules leaked when they were heated over the melting point of salt since that the relatively porous kaolin shell could be infiltrated with liquid salt because of their good wettability. However, the double shells coated capsules could prevent the leakage of salt since that the inner EG layer was repellent to liquid salt. The double shells coated macrocapsules showed good stability and high durability for long-term use, as confirmed by a cycling test over 300 cycles. The eutectic salt (Na2CO3/Li2CO3 = 57/43 in weight) core PCM presented a high latent heat of 313 J/g and melting point of around 498 °C. The macrocapsules with a size of 10@1.5@3 showed a high heat storage capability of 380 J/g in a temperature range of 400–600 °C. The macroencapulated carbonate eutectic salt with good heat storage capability and good thermal cycling durability can be extensively used for high-temperature heat storage applications in solar thermal power plant and industrial waste heat recovery.

Multiple Valence Bands Convergence and Localized Lattice Engineering Lead to Superhigh Thermoelectric Figure of Merit in MnTe.

MnTe has been considered a promising candidate for lead-free mid-temperature range thermoelectric clean energy conversions. However, the widespread use of this technology is constrained by the relatively low-cost performance of materials. Developing environmentally friendly thermoelectrics with high performance and earth-abundant elements is thus an urgent task. MnTe is a candidate, yet a peak ZT of 1.4 achieved so far is less satisfactory. Here, a remarkably high ZT of 1.6 at 873 K in MnTe system is realized by facilitating multiple valence band convergence and localized lattice engineering. It is demonstrated that SbGe incorporation promotes the convergence of multiple electronic valence bands in MnTe. Simultaneously, the carrier concentration can be optimized by SbGeS alloying, which significantly enhances the power factor. Simultaneously, MnS nanorods combined with dislocations and lattice distortions lead to strong phonon scattering, resulting in a markedly low lattice thermal conductivity(κlat ) of 0.54Wm K-1 , quite close to the amorphous limit. As a consequence, extraordinary thermoelectric performance is achieved by decoupling electron and phonon transport. The vast increase in ZT promotes MnTe as an emerging Pb-free thermoelectric compound for a wide range of applications in waste heat recovery and power generation.

Selection maps of dual-pressure organic Rankine cycle configurations for engine waste heat recovery applications

Dual-pressure organic Rankine cycles are widely used for engine waste heat recovery. Moreover, several dual-pressure organic Rankine cycle configurations exist. The configuration design and parameter optimisation of an optimal dual-pressure organic Rankine cycle system under different engine waste heat source conditions is difficult. Thus, an efficient and accurate selection method is required. To select system parameters for different waste heat sources quickly and accurately, this study proposes a method for constructing system selection maps. To use this method and verify its correctness, we applied it to a practical example of a dual-pressure organic Rankine cycle system selection process. The selection maps demonstrate that the best dual-pressure organic Rankine cycle system can increase the net output power and thermal efficiency by 8.34 %–28.52 % and 8.43 %–32.38 %, respectively, compared to the dual-pressure organic Rankine cycle system with the lowest net output power and thermal efficiency. After obtaining selection maps, the key parameters affecting the distribution of each selection map were analysed, as well as the map itself. The selection maps considered in this study provide a reference for appropriately selecting dual-pressure organic Rankine cycle systems for engine waste heat recovery. This research method can be extended to other areas (geothermal and solar) for waste heat recovery and other cycle configurations for optimum selection and design. In engineering applications, the selection map allows for quick and accurate determination of the best matching system for the target waste heat source, which reduces the capital and time costs of technical advice.

First experimental characterization of CaCl2 coated heat exchanger for thermochemical heat transformer applications in industrial waste heat recovery

This study aims at evaluating the performance of a heat exchanger coated with CaCl2 (PVA polyvinyl alcohol used as binder) for Thermochemical Heat Transformers (THT) applications in industrial waste heat recovery.For this purpose, an experimental test bench has been built allowing to test operating temperatures up to 160 °C. A model heat exchanger plate is used to test two configurations: a thick layer of CaCl2 to model a packed bed reactor (used as reference) and a CaCl2-PVA deposit to model a coated reactor.For the packed bed configuration, results comparable to that of the literature are obtained with a specific power of 180 W/kg obtained for a temperature lift of 60 K. A high sensitivity to temperature lift is identified with a decrease of the specific power down to 38 W/kg for a lift of 77 K. The coated heat exchanger configuration achieves significantly higher performance with a specific power up to 341 W/kg for a temperature lift of 63 K. However, the analysis of the repeatability tests highlights a rapid change in temperature profiles highlighting a change in properties of the CaCl2/PVA compound material. Next steps will consist in enhanced material formulation and change in deposit protocol and to move to work at small reactor scale to assess system performance.

The Mechanism behind the High Thermoelectric Performance in YbCd&lt;sub&gt;2-x&lt;/sub&gt;Mg&lt;sub&gt;x&lt;/sub&gt;Sb&lt;sub&gt;2&lt;/sub&gt;

YbCd&lt;sub&gt;2&lt;/sub&gt;Sb&lt;sub&gt;2&lt;/sub&gt; is a promising Zintl compound for waste heat recovery applications due to its low thermal conductivity, originating from its complex crystal structure. Many strategies such as alloying or doping have been suggested to further reduce the thermal conductivity of YbCd&lt;sub&gt;2&lt;/sub&gt;Sb&lt;sub&gt;2&lt;/sub&gt; to improve its thermoelectric performance. However, the effects of alloying or doping on the electronic transport properties of YbCd&lt;sub&gt;2&lt;/sub&gt;Sb&lt;sub&gt;2&lt;/sub&gt; have not been evaluated in detail. Here, previously reported thermoelectric properties of YbCd&lt;sub&gt;2-x&lt;/sub&gt;Mg&lt;sub&gt;x&lt;/sub&gt;Sb&lt;sub&gt;2&lt;/sub&gt; (&lt;i&gt;x&lt;/i&gt; = 0, 0.2, 0.4) with drastic thermal conductivity suppression were evaluated using the Single Parabolic Band (SPB) model and Callaway von Bayer (CvB) model. The SPB and CvB models evaluate any changes in electronic band parameters and phonon scattering strength, respectively, due to Mg alloying. Based on the SPB model, Mg alloying deteriorated the weighted mobility, mostly due to non-degenerate mobility reduction. However, the magnitude of point-defect phonon scattering significantly increased with Mg alloying, as evaluated by the CvB model. As a result, the maximum &lt;i&gt;zT&lt;/i&gt; is achieved when x = 0.4 at 700 K despite the decreased electronic transport properties from Mg alloying. Our work suggests that carefully designed alloying can improve the thermoelectric performance of the Zintl compound even when it changes its electronic and thermal transport properties in opposite directions.