The friction of the orbiting scroll leads to large power consumption and low energy efficiency of the scroll compressor. The common methods to solve this problem are high cost and a complex process. Considering special structures and operating principles to apply the coating technology on the scroll compressor is a new subject. Given the material of the orbiting scroll being aluminum alloy, the unbalanced magnetron sputtering technology for the orbiting scroll of the scroll compressor was chosen and the Cr transition layer was coated to enhance the bonding strength. Moreover, we innovatively performed an experiment to verify the feasibility of unbalanced magnetron sputtering film coating technology for the diamond-like carbon film coated in the scroll compressor. This article elaborates the parameter test methods of the film properties before and after experiments and the experimental system components. The results showed that the diamond-like carbon film has low coefficient and high bonding strength, which renders it a good wear-reducing effect and an excellent self-lubricating property. Due to the thin film layer and high operating temperature, the thickness should be increased to raise the abrasion resistance. The refrigeration system with the scroll compressor coated with the diamond-like carbon film can satisfy the national standard conditions with low Vickers hardness. Its performance was improved at low speed. Therefore, the unbalanced magnetron sputtering with increased Cr bond layer is a feasible and appropriate technology for coating diamond-like carbon film.

Frosting and fogging of automobile windshields is a common problem that emerges in daily driving. It is important and essential to quickly and completely defrost the windshield for safety purposes. In this study, a three-dimensional mathematical model was applied to investigate the flow distribution and flow characteristics on the windshield of a medium-size Model N800 truck. The simulation results were first compared with experimental data. The results showed that the simulation model could reliably predict the defrosting performance on the windshield. This model was then used to optimize the design of the defrosting duct that comprised the main part of the defroster. It was found that the guide plate and outlet position of the defrosting duct were the two major factors affecting the defrosting performance. Therefore, the guide plate was first optimized and the defrosting performance was analyzed. The results showed that the average pressure loss dropped by 21.56%, while the defrosting efficiency at the front white zone was improved to 89%. The position of the outlet of the airflow was further studied. The results showed that the defrosting efficiency at the front zone could be further improved to 99%.

The valve motion strongly couples with the differential pressure between the cylinder and the suction and discharge plenum, which has a significant influence on the performance of the refrigerator compressor. To examine the interaction between the pressure and the reed valve motion, this paper presents an experimental investigation into the inner workings of the refrigerator compressor, particularly the p-V diagram and the motion of the suction valve. The refrigerator compressor was modified to conveniently mount the sensors. Three pressure sensors were installed to measure the p-V diagram and pressure pulsation, while a strain gauge was employed to measure the motion of the suction valve. The interaction between the differential pressure and the valve motion were clearly observed from the experimental results. It was found that there was a considerable power loss up to 14.5% in the suction process under experimental conditions. The sticky force of the oil had a significant effect on both the motion of the suction valve and the suction phase of the compressor. The delayed opening of the reed valve increased the amplitude of the pressure pulsation in the suction plenum. The experimental method which integrates the pressure variety and the valve movement proposed in this paper could contribute to the efficient testing and the optimization of the refrigerator compressor.

Because of its low concentration and low energy in an organic Rankine cycle (ORC) system, more than 50% of low-grade thermal energy with a temperature below 300 °C is not taken seriously. The relationship between changeable working condition parameters and operating parameters is typically not taken into account in a model while studying ORC systems. It is insufficient to analyze the system performance changes solely on changes in the performance parameters of the heat exchangers. Furthermore, a model perspective of the system control solution is absent from the steady-state control of the system when the heat source varies. In this paper, we created a system model for the application scenario of a 100–200 kW ORC system with brazed plate heat exchangers in order to address the aforementioned issues using MATLAB R2016b. Additionally, a sensitivity analysis of the system was conducted based on heat exchangers of performance variations. In addition, a modeling computation and adjustment scheme were put forth to guarantee that the system could continue to produce steady power production even when the temperature of the heat source fluctuated. Preliminary results showed that the system’s internal parameters included its evaporation pressure and condensation temperature. An increase in evaporation pressure will reduce the mass flow rate and heat flux of an evaporator, thus reducing the heat transfer coefficient. The two-phase region of the evaporator accounted for the highest proportion, of 70.22%, and continued to increase to 75.83%, followed by the supercooling region, and gradually decreasing. The utilization rate of the evaporator decreased from 74.85% to 38.32%. The system output power increased first and then decreased, with a maximum value of 153.11 kW. The system efficiency increased from 5.74% to 11.04%. The increase in condensation temperature increased the proportion of the two-phase region and the superheating region, and the mass flow rate did not change much. The increase in heat flux increased the heat transfer coefficient from 1721.31 W/(m²·K) to 2374.77 W/(m²·K), and the utilization rate of the evaporator decreased from 70.56% to 51.91%. The aforementioned change rules were used in the building of the steady-state regulation model to balance out the changes in the generating power as the heat source temperature increased. The model output was cross-checked and validated against pertinent experimental test literature data. The results of this research can serve as a valid and useful guide for ORC system design and practical applications.

The refrigerant mass flow rate of a refrigerator compressor can only be measured by a mass flow meter and heat balance method. This paper focuses on the expansion and compression phase in which the compressor cylinder is closed, and proposes a measurement method of instantaneous mass flow of the refrigerator compressor. The comparison of the experimental pressure variation in the p–V diagram and the theoretical adiabatic process implied that the expansion and compression process of the refrigerator compressor approximated the adiabatic process. Based on the approximations and the experimental p–V diagram, a calculation method for refrigerant mass in the cylinder during the expansion and compression phase is proposed. Subsequently, the mass flow of the refrigerator compressor can be obtained. Furthermore, compared with experimental data and based on the method proposed in this paper, the error of the mass flow rate obtained is less than 3.13%. Based on this calculation method and the experimental p–V diagram, the influence of suction pressure on compressor performance is investigated.