Analysis of Optimal Injection Ratio of Vapor Injection Heat Pump for Electric Railway Vehicles

Air-source heat pump with vapour injection is a prospective efficient heating method for electric railway vehicles in cold regions. A heating performance analysis modelling for air source heat pump with vapour injection is set up for performance optimization in this paper. The maximum errors of the program are within 15%. Heating performance, as well as the optimal injection ratio is analysed. The optimal injection ratio varies mainly from 0.12 to 0.3 under the typical working condition of railway vehicles in winter. It goes up with increasing inlet air temperature of condenser and goes down with increasing ambient temperature. The ambient temperature has very little effect on the optimal injection temperature of the internal heat exchanger. The results indicate that the expander valve opening of the injection branch can be controlled by its outlet temperature to get the optimal heating performance

Experimental investigation on an integrated thermal management system with heat pipe heat exchanger for electric vehicle

An integrated thermal management system combining a heat pipe battery cooling/preheating system with the heat pump air conditioning system is presented to fulfill the comprehensive energy utilization for electric vehicles. A test bench with battery heat pipe heat exchanger and heat pump air conditioning for a regular five-chair electric car is set up to research the performance of this integrated system under different working conditions. The investigation results show that as the system is designed to meet the basic cabinet cooling demand, the additional parallel branch of battery chiller is a good way to solve the battery group cooling problem, which can supply about 20% additional cooling capacity without input power increase. Its coefficient of performance for cabinet heating is around 1.34 at −20 °C out-car temperature and 20 °C in-car temperature. The specific heat of the battery group is tested about 1.24 kJ/kg °C. There exists a necessary temperature condition for the heat pipe heat exchanger to start action. The heat pipe heat transfer performance is around 0.87 W/°C on cooling mode and 1.11 W/°C on preheating mode. The gravity role makes the heat transfer performance of the heat pipe on preheating mode better than that on cooling mode

Landslide numerical forecasting mode based on physical- mechanical mechanism: Overviews, challenges and opportunities

Landslide forecasting and prediction is a frontier scientific issue that has received widespread attention in the field of geohazard prevention and control. The current research framework focuses on the deformation behavior characteristics and external dynamic factors of landslides and faces the dual bottleneck problems of low universality and low prediction accuracy.Based on the current research status, this paper systematically clarifies the connotation of the rheological-mechanical behavior and strength weakening effect of the sliding zone, explicates the evolution mechanism of the progressive failure of the landslide, summarizes the types of landslide prediction models, and introduces the typical models among them.Based on the comprehensively existing achievements, it is pointed out that the main problems of the current research are: ①the physical-mechanical models of landslide evolution are required to be extended; ②the prediction and forecasting models fail to fully integrate with landslide evolution and physical-mechanical model; ③the compatibility problem between physical-mechanical model prediction and multi-field monitoring data have not been practically solved. Given the above problems, the challenges of landslide prediction and forecasting models based on physical-mechanical processes are elaborated. Based on multidisciplinary integration and intersection, a new research strategy for landslide forecasting study is proposed. The new strategy requires the establishment of a physical-mechanical model of the landslide evolution process based on the structural properties and rheological-mechanical behavior of the slip zone. On this basis, a numerical forecasting mode for landslides is established by closely integrating real-time multi-field monitoring data that enables real-time dynamic updating of landslide physical-mechanical processes. This strategy is designed to achieve a theoretical and technical breakthrough

Molecular insights into the mechanisms of a leaf color mutant in Anoectochilus roxburghii by gene mapping and transcriptome profiling based on PacBio Sequel II

Abstract Plants with partial or complete loss of chlorophylls and other pigments are frequently occurring in nature but not commonly found. In the present study, we characterize a leaf color mutant ‘arly01’ with an albino stripe in the middle of the leaf, which is an uncommon ornamental trait in Anoectochilus roxburghii. The albino “mutant” middle portion and green “normal” leaf parts were observed by transmission electron microscopy (TEM), and their pigment contents were determined. The mutant portion exhibited underdevelopment of plastids and had reduced chlorophyll and other pigment (carotenoid, anthocyanin, and flavonoid) content compared to the normal portion. Meanwhile, comparative transcript analysis and metabolic pathways mapping showed that a total of 599 differentially expressed genes were mapped to 78 KEGG pathways, most of which were down-regulated in the mutant portion. The five most affected metabolic pathways were determined to be oxidative phosphorylation, photosynthesis system, carbon fixation & starch and sucrose metabolism, porphyrin and chlorophyll metabolism, and flavonoid biosynthesis. Our findings suggested that the mutant ‘arly01’ was a partial albinism of A. roxburghii, characterized by the underdevelopment of chloroplasts, low contents of photosynthetic and other color pigments, and a number of down-regulated genes and metabolites. With the emergence of ornamental A. roxburghii in southern China, ‘arly01’ could become a popular cultivar due to its unique aesthetics

Experimental Analysis of the Discharge Valve Movement of the Oil-Free Linear Compressor in the Refrigeration System

In a linear compressor, the valve motion significantly affects the thermodynamic efficiency and the compressor’s reliability, especially in oil-free conditions. To better understand the dynamic behavior of the discharge valve, a real-time test bench was built. The piston movements and dynamic pressure in the cylinder were also observed to obtain the synchronizing characteristics among the reed valve motion, cylinder pressure, and piston motion. Observing the motion of the discharge valve visually, the discharge valve flutters due to the change in the form of the cylinder pressure, the delayed opening of the valve is caused by the inertia of the valve itself, and additional displacement fluctuations are present. This paper presents the dynamic behavior of the discharge valve under different discharge pressure/operating frequency/piston stroke/clearance length conditions. The results show that the valve flutters increase, the mean displacement of the valve increases, and the duration of the discharge increases when the discharge pressure decreases. When the operating frequency increases, the duration of the discharge decreases, while the mean displacement of the valve increases. For a high stroke or a low clearance length case, the duration of the discharge increases, while the valve flutters increase due to the pressure fluctuations in the cylinder. Through analyzing the synchronizing characteristic among the valve movements, piston movements, and cylinder pressure, it is shown that the phenomenon of the delayed opening valve is much worse for a low stroke or a high operating frequency case. In addition, the delayed closing of the valve appears for a high operating frequency case (75 Hz)

Experimental Research on the Effect of Oil Charge Ratio on the Cooling Performance of CO2 Air Conditioning System for Electric Vehicles

From the perspective of the engineering application, the influence of the oil charge ratio on the cooling performance of the electric vehicle CO2 air conditioning system is experimentally studied in this paper. An online test device for oil circulation rate is set up on the built CO2 air conditioning system test bench. The experiment is conducted under different ambient temperatures and compressor speeds in the fresh air mode. As the oil charge ratio increases, the oil circulation rate increases as well as the oil mass flow rate, while the refrigerant mass flow rate decreases slightly. Under the refrigerant charge amount of 550 g and ambient temperature of 35 °C and 40 °C, this system reaches its best cooling performance when the oil charge ratio is in the range of 20% and 25%. And the maximum COPs are 2.46 and 2.36, respectively. The increase in the oil charge ratio is beneficial to the improvement of the isentropic efficiency and the volumetric efficiency of the compressor. The change in oil circulation rate has less effect on the pressure drop in the gas cooler than that in the evaporator