## 1 Introduction  
Increased fossil fuel consumption causes environmental pollution, global warming, and energy crisis; waste heat recovery is considered a promising technology for solving these problems [1; 2; 3]. The waste heat utilization of internal combustion engine (ICE) can effectively reduce the use of fossil fuels and is crucial for saving energy and reducing emission because oils consumed by ICE account for approximately 60% of the total oil consumption, and more than 55% of fuel energy is emitted through waste heat [4; 5; 6; 7]. Among all of the existing solutions for the waste heat utilization of ICE, organic Rankine cycle (ORC) is a promising technology. ORC uses organic working fluids; this technology has advantages of simple structure, favorable applicability, and user-friendliness over conventional steam Rankine cycle and is ideal for utilizing medium-to-low temperature heat sources (<350 \({}^{\circ}\)C) [8; 9; 10; 11]. Many researchers have conducted studies on ICE waste heat recovery using ORC and have discovered the favorable potential of this technology [12; 13; 14; 15; 16; 17; 18]. [PERSON] et al. [12] used ORC to recover waste heat of diesel engine using alkanes as working fluids. Their results showed that cyclohexane and cyclopentane are the most suitable working fluids through comprehensive consideration. [PERSON] et al. [13] performed a thermodynamic analysis of ICE waste heat recovery using ORC, benzene, R11, and R134a as working fluids and considered different cycle configurations. Their results indicated that the overall efficiency of ORC is better by 12% than when ORC is not applied. [PERSON] et al. [17] designed an optimized ORC for marine diesel engine waste heat recovery and conducted economic and off-design analyses. Their results demonstrated that an optimized ORC is technically feasible and economically attractive. ICE waste heat resources mainly consist of engine exhaust and jacket cooling water; given the high temperature of engine exhaust gas when a single-stage ORC is applied for waste heat recovery, the match between an engine exhaust gas and a high-temperature loop (HTL) may exacerbate, and the utilization of engine jacket cooling water is low [19; 20]. Therefore, many researchers have adopted a dual-loop organic Rankine cycle (DORC) for ICE waste heat recovery and conducted system analysis, parametric analysis, and configuration comparison. [PERSON] et al. [21; 22; 23] designed several systems for utilizing the ICE waste heat. Their results showed that R143a and R1234 yf are favorable working fluids for low-temperature loop (LTL), and low condensation temperature can improve system performance. [PERSON] et al. [19] investigated a regenerative transcritical system for ICE waste heat recovery. Their results showed the toluene is a favorable option for HTLs. [PERSON] et al. [24] developed a novel DORC to recover waste heat from exhaust gas, intake air, and coolant. Their results indicated that DORC can relatively improve output power by 14-16% in the peak of the effective thermal efficiency region. [PERSON] et al. [25] studied a DORC for diesel engine waste heat recovery under various operating conditions; these authors selected R245 fa as the working fluid and discussed performance on the basis of the first and second laws of thermodynamics. Their conclusion revealed that DORC can enhance the system thermal efficiency by 13% in comparison with the original system. [PERSON] et al. [26; 27] used DORC to harness the wasted heat from ICE and calculated the performance of a combined engine-ORC system under the entire operating region of an engine. Their results indicated that the relative increment rate of net power output can reach 22% in the peak thermal efficiency region. [PERSON] and [PERSON] [28] investigated a DORC waste heat recovery system, used water and R1234 yf for HTLs and LTLs, and analyzed the thermodynamic properties of a waste heat recovery power generation system.