论文总字数：72158字

摘 要

冷藏运输车是冷链物流中极为重要的一环，担负着易腐食品、医疗用品和部分电子元件运输的重任，具有很大的经济价值和研究价值。本论文将设计一辆载重1100kg的轻型冷藏保温车，厢体结构为“三明治”结构，以聚氨酯泡沫作为隔热材料，内外蒙皮材料选择玻璃钢，兼顾保温性能和机械强度。厢体内尺寸为，隔热材料和蒙皮厚度分别为和。本文将使用CATIA建模软件对厢体和影响厢体制冷保温热性能的部件进行三维建模；并通过ANSYS的Workbench平台中的CFX模块对装有货物苹果时的厢内空气进行在一定边界条件条件下的温度场仿真和流场仿真，冷藏厢内气流组织的数据模型采用带有Scalable wall function的 k-Epsilon模型。本文还对通过对隔热车厢的传热系数和热负荷的计算进而对制冷装置的制冷量进行计算。

Abstract

Refrigerated transport vehicle is an important link in the cold chain logistics, which is responsible for the transportation of perishable food, medical supplies and some electronic components. It has great economic value and research value.This paper will design a lightweight refrigerated insulation vehicle with a load of 1100kg. The compartment structure is a "sandwich" structure. Polyurethane foam is used as the heat insulation material.The body size of the compartment is, the heat insulation material and the thickness of the skin are respectively and.In this paper, CATIA modeling software will be used for three-dimensional modeling of the box body and the parts that affect the cold and thermal insulation performance of the box system.Through CFX module in Workbench platform of ANSYS, temperature field simulation and flow field simulation are carried out for the air in the compartment loaded with apples under certain boundary conditions. The data model of airflow organization in the refrigerated compartment adopts k-epsilon model with Scalable wall function.This paper also calculates the heat transfer coefficient and heat load of the heat-insulated compartment, and then calculates the refrigerating capacity of the refrigerating device.

Keywords

Refrigerating and insulating car, refrigerating device, box body, simulation

目录

摘要 I

Abstract II

Keywords II

Chapter 1 Introduction 1

1.1 Background and significance of the topic 1

1.2 Research status and development direction of refrigerated thermal insulation vehicle at home and abroad 4

1.2.1 Research status of refrigerated thermostats at home and abroad 4

1.2.2 Future development direction of refrigerated and insulated vehicle 5

1.3 Chapter summary 6

Chapter 2 Overall design of refrigerated and insulated vehicle 5

2.1 Selection of refrigerated and insulated vehicle 5

2.1.1 Selection of refrigerated and insulated vehicle tonnage 5

2.1.2 Selection of refrigeration mode for refrigerated and insulated vehicles 6

2.2 Design of refrigeration device for refrigerating and insulating vehicle 8

2.2.1 Arrangement of refrigerating devices for refrigerating and insulating vehicles 8

2.3 Structure and materials of refrigerated and insulated compartment 9

2.3.1 Structure selection of insulated compartment 10

2.3.2 Selection of insulation materials and skin materials 11

2.3.3 Selection of carriage door structure 12

2.4 Chapter summary 12

Chapter 3 Calculation of refrigerating capacity of refrigerating device 13

3.1 Calculation of heat transfer coefficient of insulated compartment 14

3.2 Calculation of thermal load of insulated carriages 19

3.3 Calculation of refrigerating capacity of refrigerating device 22

3.4 Chapter Summary 22

Chapter 4 Modeling and simulation of refrigerated and insulated vehicle 23

4.1 Cold storage and insulation vehicle modeling. 23

4.1.2 Establishment of physical model of refrigerated and insulated car 23

4.1.2 Selection of airflow model of refrigerated and insulated vehicle 26

4.2 Simulation of flow field and temperature field inside refrigerated and insulated vehicle 26

4.2.1 Setting of boundary conditions 28

4.2.2 Analysis of simulation results of temperature field in the compartment 29

4.3 Chapter summary 31

Conclusion 32

Reference 33

Thanks 35

Chapter 1 Introduction

1.1 Background and significance of the topic

Since the 1970s and 1980s, the distribution mode of domestic living materials has changed from the original arrangement by the government to self-regulation, from the former state controlling the whole situation, mobilizing and distributing refrigerated vehicles loaded with food and commodities, to the refrigerated vehicles operating independently and transporting according to the market demand. As a large country of agricultural and animal husbandry production, with the increase in the output of food and other products or even more supply than demand, coupled with the cancellation of planned supply, the distribution ratio of long-distance transportation declined, while the distribution ratio of short-distance transportation began to rise. Along with our country urbanization, population, the demand for fresh perishable food is also rapidly increasing, cold chain transportation is the main fresh transportation means, including highway refrigerated transport along with the development of related technology and social infrastructure, from 30 years ago accounted for 30% to 75% in 2019, the second railway refrigerated transport, accounting for more than 12%.At present, the main product categories of refrigerated vehicles are thermal insulation vehicles (only heat insulation structure without refrigerating units) and refrigerated vehicles (the lower limit of temperature can reach -18℃). The proportion of refrigerated vehicles and fresh vehicles also increases year by year.^[3]The transportation object has also developed from the former structure of livestock, poultry, seafood and river food to a comprehensive food coverage, and has a huge demand in military industry, electronic components, medical facilities and other aspects. As an important refrigerated vehicle carrier, there are more than 4 million refrigerated vehicles of various types in the world, with an annual growth rate of 2.5%.Since the state introduced policies to encourage the development of the cold chain transportation industry 12 years ago, the domestic refrigerated vehicle transportation industry has been developing rapidly and steadily. By 2019, the number of refrigerated vehicles in China was about 214,700, an increase of 34,700 compared with 2018.Among them, the growth of refrigerated vehicles in east China leads the country, while light vehicles and diesel vehicles are favored by the market.

In view of the importance of this issue, countries around the world often promote and regulate the use of refrigerated transport technology in the form of legislation or regulations. In recent years, China's supply chain logistics has developed rapidly. In 2018, the total demand of the food cold chain logistics industry has reached 481 million tons, and it is estimated that the total demand of the cold chain logistics industry will reach 650 million tons in 2025.At the same time, with the rapid development of the Internet industry in recent years, the combination of the Internet and the food industry, people's demand for fresh and safe food is growing day by day. The development of e-commerce platforms, such as hema fresh fresh product distribution, is also further stimulating the increase in demand for refrigerated vehicles. In addition, the policy encourages the rapid development of cold chain logistics, and the scale of refrigerated vehicle market keeps growing.^[9]

However, there is still a big gap between China and developed countries in the refrigerated transport rate of the above food. Despite growing demand for fresh produce, the circulation of fresh produce remains at a low level.In 2018, total food cold-chain logistics accounted for only 1.7 percent of total social logistics.The refrigeration effect of preserving fresh products is not enough, the transportation equipment is backward, and the cold chain rate is low in the whole process, leading to the phenomenon of "broken chain". In the four years since 2010, the number of refrigerated vehicles on China's roads has been growing at an average speed of nearly 30 percent per head.In 2015, with the economic growth slowing down, the commercial automobile market in China experienced a cold winter, which was relatively sluggish. However, stimulated by the rising demand for food and drugs, the refrigerated vehicle market grew against the trend and is expected to exceed 200,000 units in 2020.However, in terms of the number of thousands of refrigerated vehicles, there are only two in the United States, but only 0.038 in China. Obviously, China's existing refrigerated transportation industry is not big enough to meet the market requirements of low-temperature logistics industry.

It is not only the change of grain structure that urges the development of refrigerated automobiles. From the perspective of the laws and regulations promoted by the state, the policy and legal environment are improving, and the standardization process is accelerating, which is also escorting the development of cold chain logistics.At the beginning of 2016, the state council issued the opinions of the state council of the CPC central committee on implementing the new concept of development and accelerating agricultural modernization to achieve the goal of building a moderately prosperous society in all respects, which clearly stated that "we should improve the trans-regional cold chain logistics system for agricultural products, carry out standardized demonstration of the cold chain, and carry out the pre-cooling project for the production areas of featured agricultural products."In July 2016, premier li keqiang clearly put forward the idea of "encouraging the development of cold chain logistics" at the executive meeting of the state council.In response to the implementation of the above policies, various departments and provinces and cities have successively issued and detailed the development plan of cold volume logistics. For example, Hainan province has issued the government to support logistics enterprises to purchase small refrigerated vehicles and give financial subsidies according to 40% of the investment.Above all, illustrates the state food and drug supervision in increasing, and one of the important link of cold chain transportation is becoming more and more valued, in such form, not only is the development of road transportation, but also to carry out research on energy efficient and environmentally friendly emerging refrigerated car has important practical significance, refrigerator car market is the inevitable trend.

With the change of people's living mode, people's demand for materials is increasingly diversified. The booming development of fresh e-commerce has also accelerated the flow of various materials between different regions. Demand patterns of our products "in many varieties, small batch" the pattern of development, that's right, in the short range of cold-chain transport put forward higher requirements, the temperature range of single refrigerated trucks can only transport goods with the same preservation temperature, with batch if there are different temperature requirements of the goods, need to purchase more refrigerator car, can make in the, in the short-distance distribution, the phenomenon of the fill, reduces the utilization of refrigerated truck. The emergence of refrigerated vehicles in the multi-temperature region has solved this problem in a timely manner. It is flexible and efficient to transport goods with different temperature demands in the same batch. The proposal of this concept has attracted the attention of researchers in the cold-chain transportation industry. During the 7-day 25th international refrigeration conference held in late August 2019, the future development direction of refrigeration technology was summarized into two aspects: lower GWP refrigerants and more energy efficient technologies, and green, environmental protection, energy conservation and food supply should be the key development direction of the refrigeration industry.

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