Sun Jingchun, Lv Ding and Wu Fan
The purpose of this paper is to model the trend of natural gas supply and demand in China in different circumstances from 1990 to 2050.
Abstract
Purpose
The purpose of this paper is to model the trend of natural gas supply and demand in China in different circumstances from 1990 to 2050.
Design/methodology/approach
The related factors were selected from references and classified into three categories such as endogenous, exogenous, and excluded factors. The three sub‐models of supply, demand and their interconnection were built and integrated. The impacts of natural gas resources, the investment of gas industry and the energy structure over natural gas supply and demand were analyzed based on scenario analysis.
Findings
The impact of energy structure in China is more evident compared to natural gas resources and the investment level.
Research limitations/implications
Import and transportation of natural gas will have growing impacts on the supply and demand in China when the model is applied.
Practical implications
A very useful method to analyze the equilibrium of natural gas supply and demand.
Originality/value
The paper presents a new prediction model of natural gas supply and demand in system dynamics. The paper is aimed at the researchers and decision makers in energy industries, especially in the fields of energy prices.
Details
Keywords
Dongfang Sun, Jingchun Tang, Xiuping Zhang, Xudong Yuan, Yue Qian, Fangping Ye, Bin Ye and Bin Jiang
The leakage problem caused by machining error, assembly error, wearing and thermal deformation has been the main factor hindering the development of scroll compressor. This paper…
Abstract
Purpose
The leakage problem caused by machining error, assembly error, wearing and thermal deformation has been the main factor hindering the development of scroll compressor. This paper aims to investigate the lubrication characteristics of radial clearance and further optimize the radial clearance, which can reduce the leakage in the tangential direction of the working chamber.
Design/methodology/approach
This paper establishes a model of radial clearance oil film lubrication in scroll compressor. And, the method to solve the Reynolds and energy equations is presented, as well as the dimensionless and discretization by finite element difference method. To verify the established model, performance experiment of scroll compressor for electric vehicle air conditioning system is also carried out.
Findings
Based on the presented model, the temperature field and distribution of the oil film in the radial clearance are analyzed. And the influence of the structural parameter on the radial clearance is further discussed. The optimum radial clearance could be achieved at β = 40°–42°, where the orbiting scroll is in the state of rotary balance. And, the simulation results coincide well with the experimental results.
Originality/value
This work provides an effective model to evaluate the lubrication characteristics of radial clearance in scroll compressor, which can provide guidance for the design of scroll compressor.
Details
Keywords
Zujian Shen, Fei Geng, Xinxin Fan, Zhichen Shen and Haiyan Wang
This paper aims to investigate and prepare the composite polyurea greases with excellent thermal stability and tribological properties.
Abstract
Purpose
This paper aims to investigate and prepare the composite polyurea greases with excellent thermal stability and tribological properties.
Design/methodology/approach
In this paper, composite Ba-based (Ba, barium) tetra-polyurea lubricating greases were prepared with two different methods: mixing Ba-based gelatinizer and tetra-polyurea gelatinizer by a physical method; and introducing barium carboxylate into tetra-polyurea molecules by a chemical method. The properties of the products, such as heat stability, water resistance and friction performance, were analyzed with thermogravimetry, water-resistance test and four-ball friction test.
Findings
The results indicated that the products obtained by chemically introducing barium carboxylate into tetra-urea molecules showed better elevated temperature tribological properties, and the disadvantages of the polyurea greases with high temperature hardening were also obviously improved. The cone penetration rate at 180°C for 24 h is only 3 per cent. The friction coefficient can be decreased to 0.44 and the last non-seizure load value was increased from 560 N to 1,120 N without any other additives.
Originality/value
The research is significant because the prepared composite grease showed excellent performances, such as the outstanding thermal stability, water resistance and excellent extreme pressure and anti-wear properties, which may be widely applied in steel, metallurgy, bearings and other industrial fields.