Refrigeration professional post internship report

Foreword

New semester, new weather, new beginning. In the face of graduation, we are preparing to step into the society. In order to better link the professional knowledge of refrigeration and refrigeration technology to the actual life, production and work, we professionally held a job mobilization meeting on the afternoon of September 7. At the meeting, the three teachers Li Jianxiong, Wang Hong and Li Haoxue emphasized the importance and purpose of this internship and the requirements during the internship period from different angles and aspects, and made specific arrangements for the internship schedule. The last three teachers emphasized that during the internship, the concept of “theory is linked to reality” was implemented in the actual production internship and collective outing activities. Everyone must obey the arrangement of teachers and class cadres, and the internship unit must have “safety”. The first "consciousness."

One: Internship purpose:

Contact with the actual, combined with the actual, learn to use, learn to gain.

Two: three directions of job internship:

1. The drawing, reading and drawing design of the refrigeration system of the cold storage and central air conditioning.

2. The whole process of processing and production of automobile air conditioners and household air conditioners.

3. Construction, installation and commissioning of central air conditioning in buildings such as shopping malls and office buildings.

Third: the requirements for job internship:

1. All students are required to participate as required.

2. In order to pay attention to personal safety, the factory must comply with the order and regulations of the factory, and pay attention to the machines and production lines away from the workshop.

3. During the internship process, you should pay attention to the diligence and study, learn what you have learned, and apply what you have learned.

4. In vitro activities should pay attention to the overall quality of the professional and the overall image of the profession.

Four: Visit the internship schedule:

I. Internship process of Henan Xinxiang Asian Beer Co., Ltd.

1. On the first day, Wang Hong teacher led a team to Henan Xinxiang Asian Beer Co., Ltd. First, the Hu security officer gave each of us a visitor certificate, entered the factory and gave us a brief description of the factory. Provisions, then we will enter the conference room on the third floor. The security officer in the conference room showed us the creation, development and growth of Xinxiang Asian Beer. Finally, the Hu security officer gave us a brief introduction to the beer production process:

Wheat mashing fermentation canning

The following is a schematic diagram of the production process:

The Hu security officer told us about some of the considerations for entering the workshop, and we entered the internship workshop in two groups.

Our first group first came to the first floor of the refrigeration workshop. There were 6 units on the first floor. Due to the small demand, only the 6# unit was working, and the other 5 units were stopped. Among them, there were 3 screw machines and 3 centrifugal machines. Machines, 1#, 2#, 3# are 8as17 ammonia piston refrigeration units, each with a cooling capacity of 512kw and a shaft power of 142kw. 4#, 5#, 6# is the nominal refrigeration capacity of the screw refrigeration unit of 784kw, nominal operating conditions: evaporation temperature: -7 °C, condensation temperature: 35 °C, because the refrigeration unit is working at the same time, their working pressure display Not the same, only the 6# unit is working, its working conditions: suction pressure: 0.3mpa, exhaust pressure: 0.9mpa, oil pressure: 0.85mpa, internal pressure ratio: 7.5. The motor power is 220kw, and the area of ​​the matching condenser is 32m2. In addition, the secondary oil fraction of the 5# unit is ka20c type. From the scene, it can be seen that the tubes at the entrance of the evaporator are frosted, and the exterior paints of different pipes are also different.

After reading the first layer, we exchanged the second layer with the second group to see the evaporator in the second floor of the refrigeration workshop. There are 5 horizontal condensers on the second floor:

Evaporator

The Hu security officer told us how the evaporators are connected together. Each evaporator is connected with a gas-liquid separator. The four evaporators are connected through various pipes and valves, and the cooling capacity is compared. Large, there is a larger refrigerant tank outside the second floor.

The top of the building is an evaporative condenser with a total of four evaporative condensers, of which only one is in the working evaporator. After listening to the introduction of the Hu security officer, our internship at Xinxiang Asia Beer Co., Ltd. was successfully completed.

Below is a drawing of the refrigeration system for my internship at the Xinxiang Asian Beer Tour:

2. Internship experience: Through this internship, I learned more about the working condition of the refrigeration unit, and better understood the functions of the various components of the refrigeration unit and their relative positions, which laid a solid foundation for my future installation and maintenance in the refrigeration industry.

Second: the city government central air-conditioning system visit internship

1. The next morning, Li Haoxue led the team to the city government building. The director of the Municipal Administration Bureau led us to the basement to visit the refrigeration unit. Their refrigeration unit is also a combination of a screw machine and a centrifuge. The following describes the working characteristics of the screw machine and the centrifuge:

The screw refrigeration compressor is a kind of rotary refrigeration compressor, and has both the piston type and the power type.
1) Compared with reciprocating piston refrigeration compressors, screw refrigeration compressors have a series of advantages such as high speed, light weight, small size, small footprint and low exhaust pulsation.
2) The screw refrigeration compressor has no reciprocating mass inertia force, good dynamic balance performance, stable operation, small vibration of the machine base, and the foundation can be made smaller.
3) The screw type refrigeration compressor has a simple structure, a small number of parts, and no wearing parts such as a gas valve and a piston ring. Its main friction parts such as a rotor and a bearing have high strength and wear resistance, and lubrication conditions. Good, thus less machining, low material consumption, long operating cycle, relatively easy to use, simple maintenance, and easy to achieve automation.
4) Compared with the speed compressor, the screw compressor has the characteristics of forced air transmission, that is, the displacement is almost independent of the exhaust pressure, and there is no surge phenomenon at a small displacement, and the work is broad. In the range of conditions, high efficiency can still be maintained.
5) Sliding valve adjustment is adopted to achieve stepless adjustment of energy.
6) The screw compressor is not sensitive to the liquid inlet and can be cooled by injection. Therefore, at the same pressure ratio, the discharge temperature is much lower than that of the piston type, so the single stage pressure ratio is high.

7) There is no clearance volume, so the volumetric efficiency is high.
Screw refrigeration compressors have the following drawbacks:
1) The refrigerant gas periodically passes through the suction and exhaust ports at high speed, and leaks through the gap. The compressor has a lot of noise, and noise reduction and noise reduction measures are required.
2) The machining accuracy of the space surface of the spiral rotor is high, and it needs special equipment and tools to process.
Limitations of gap seals and rotor stiffness, etc. At present, screw compressors cannot achieve higher end pressures like reciprocating compressors.

The centrifugal chiller uses electricity as the power source. The Freon refrigerant evaporates and absorbs the heat of the brine water in the evaporator for cooling. The vaporized endothermic freon vapor is compressed by the compressor into a high temperature and high pressure gas, and condensed by a water-cooled condenser. It becomes a liquid and is throttled into the evaporator through the expansion valve. Thus, 7 ° C - 12 ° C chilled water is prepared for air conditioning at the end of the air conditioner.

A fully enclosed refrigeration compressor is used.

· Working principle: The blade rotates at high speed, and the speed changes to generate pressure. It is a speed compressor.

Less moving parts, low failure rate and high reliability.

The coefficient of performance is high, generally above 5.0. 30% load operation can achieve infinite adjustment, and the energy saving effect is more obvious.

The cooling capacity of centrifugal chillers is mainly caused by water quality: the condenser and evaporator of the unit are heat exchangers. If the heat transfer tube wall is fouled, the cooling capacity of the unit will decrease, but the condenser and evaporator are in the process of designing the manufacturer. It has been considered to be easy to clean, and its cooling capacity has a long decay with the use of time, and the cooling capacity is rarely attenuated.

The average life of the centrifugal compressor is 75,000 hours. The unit freon and oil have been added, and the user can use the water and electricity on site.

The unit does not need to be overhauled, only the cleaning of the water system is required, and the maintenance cost is low.

The refrigerant r134a used in the municipal building, in which the evaporator unit area of ​​the screw unit is 1094 m2 and the condenser area is 32 m2. Cool with water.

The nameplate of the centrifugal unit: refrigerant: r134a, nominal cooling capacity 1758kw, voltage: 380v, rated power: 367kw.

During the visit, I actively learned the names, working principles and working conditions of each component. I continued to consult with Teacher Li, Director Zeng and the staff at the scene. In addition, I actively exchanged ideas with other students and gained a lot.

Finally, the director personally answered questions at the scene, and the patient had patiently answered questions about the professional problems of the students. In addition, the director once answered the employment problem raised by the students: "Now the country's economic recovery is very good, and all aspects are lack of talents. Everyone will be able to find a good job. The country needs you very much. You are the pillar of the country. You must work hard."

Three: Fat Donglai Life Square visit internship

1. On the afternoon of September 9th, Li Haoxue took us to the fat east to visit the life square to visit the internship. The refrigeration unit from Fatdong is a 19xr closed centrifugal chiller manufactured by Shanghai Hezhong-Kelly Air Conditioning Equipment Co., Ltd. First of all, let's talk about the meaning of the 19xr series model: 19xr-65-65-467-dj-s-52 19-efficient closed centrifugal chiller, 65-evaporator model, 65-condenser model, 467 - Model of the compressor, dj-motor model, s-motor type, 52-motor voltage code.

Then talk about the working process of the 19xr closed centrifugal chiller: the compressor continuously draws the refrigerant vapor from the evaporator, and the gas flow is determined by the opening degree of the vane. Since the compressor draws refrigerant to reduce the pressure of the evaporator, the remaining refrigerant in the evaporator evaporates at a relatively low temperature. The refrigerant vaporizes and absorbs the heat of the circulating water in the heat transfer tube to cool it. Get the cold water needed for air conditioning or industrial processing. After the heat in the circulating water is sucked, the refrigerant vapor is sucked into the compressor for compression, and after the compression, the temperature of the refrigerant rises, is discharged from the compressor, and enters the condenser for condensation. The relatively low temperature cooling water flows through the condenser copper tube, taking away the heat of the gaseous refrigerant to condense it into a liquid state. The liquid refrigerant enters the flash subcooling chamber from the throttle valve. Due to the low pressure in the flash subcooling chamber, part of the liquid refrigerant is flashed into a gas, and most of the liquid refrigerant is further cooled after the heat is taken up. The flash refrigerant gas condenses into a liquid outside the copper tube of the cooling water, and flows to the float valve chamber between the supercooling chamber and the evaporator. A liquid seal formed by a linear float valve in the float valve chamber prevents vapor from the subcooling chamber from entering the evaporator. When the liquid refrigerant flows through the float valve, the refrigerant flows back to the low temperature and low pressure state to evaporate, and the refrigeration cycle begins. Below is the fat east to life square refrigeration system diagram

Four: Xinxiang City, the real food factory to visit the internship:

On September 10, under the leadership of Teacher Wang, we came to the Zhenyi Food Factory to visit the internship. The true food used was different from other refrigeration cycles. The plant used a one-stage throttle to completely cool the two-stage vapor compression refrigeration cycle.

The two-stage vapor compression refrigeration cycle can reduce the pressure ratio of each stage, reduce the clearance of the refrigeration compressor, increase the gas transmission coefficient of the compressor and the actual gas transmission volume, and reduce the refrigeration capacity of the Zhengjia cycle to reduce the irreversible loss. It saves cycle energy and ensures efficient and safe operation.

The intermediate throttle is: the refrigerant liquid supplied to the evaporator directly has a condensing pressure flow to the throttling process of the evaporation pressure,

The intermediate complete cooling type refers to a cooling process in which the superheated steam discharged from the low pressure stage is equalized to cool the saturated vapor of a large intermediate pressure during the intermediate cooling process.

The determination of the throttling mode is related to the type of refrigeration compressor and the stability of the cooling load of the refrigeration system. The piston chiller with a large change in the cooling load adopted by the plant should adopt one throttling; the adoption of different intermediate cooling modes The type of refrigerant is related to the refrigerant type r717 used in the plant. If the suction superheat is unfavorable to the circulating type, the intermediate cooling method should be adopted.

The installation position of the low-pressure circulating liquid storage device is related to its working principle. The working principle is similar to the working principle of the ammonia liquid separator. After the wet steam from the evaporator enters the low-pressure circulating liquid storage device from the return air pipe, the flow direction is reduced due to the steam flow rate. The change, plus the action of the baffle, separates the entrained refrigerant liquid. The dry saturated vapor is sent to the suction main pipe of the refrigeration compressor through the suction pipe, and the bottom of the liquid flow device is supplied from the liquid discharge port to the evaporator.

[1][2][3][4]

The following is a drawing of the refrigeration system of the Zhenyi Food Factory:

V: Internship in the New District Automobile Training Center:

1. The composition and function of automotive air conditioning refrigeration system

Compressor - compresses low-temperature and low-pressure refrigerant gas into high-temperature and high-pressure refrigerant gas condenser - heats the high-temperature and high-pressure refrigerant gas into a medium-temperature high-pressure liquid refrigerant drying tank - filters impurities in the refrigerant and Moisture expansion valve - the refrigerant is throttled into a low-temperature low-pressure mist, a gaseous mixture evaporator - absorbs heat to change the low-temperature and low-pressure mist, gaseous mixture into a gaseous state

The function of the air conditioning control system is to ensure the normal operation of the air conditioning and refrigeration system, and also to ensure the normal operation of the engine when the air conditioning system is working. Here are the main components of the control system:
The electromagnetic clutch electromagnetic clutch is mounted on the compressor and functions to control the power transmission between the engine and the compressor.
The electromagnetic clutch mainly includes main components such as pressure plate, belt pulley and stator coil.

2) Temperature control of the evaporator

The evaporator temperature switch is installed in the middle of the evaporator. When the surface temperature of the evaporator is lower than a certain set value, the temperature switch automatically cuts off the electromagnetic clutch circuit of the compressor.

Condenser fan control

Many engine cooling water and air conditioning condensers are cooled by the same fan. The fan is not only controlled by the engine water temperature. At the same time, the air conditioner switch model and the pressure of the refrigeration system are used to control the high and low speed operation of the fan.

4) Refrigeration cycle pressure control

If there is a pressure abnormality in the air conditioning refrigeration cycle system, the system will be damaged. If the pressure is too low, it means that the refrigerant is too small, which will cause the compressor to be oily and damaged. If it is supplied too high, it may cause damage to system components. Therefore, high-voltage switches and low-voltage switches that monitor line pressure are usually installed in the system.

Engine idle speed control

When the air conditioner switch a/c is turned on, the control unit of the engine can receive the signal that the air conditioner is turned on, and the control unit controls the idle speed control valve to increase the passage of the idle bypass air passage to increase the intake air amount and increase the idle speed.

Then, under the leadership of Teacher Wang, we carefully and carefully visited the various parts of the new car model in the new area, and how the various components are connected by pipes. The functions and interconnections of the various refrigeration system components. . By understanding I know: the water tank is cooling the engine. At the same time, the form of the heat sink of the refrigeration system is: cascading. Let me describe what I saw about the new district laboratory. Here is the cooling schematic of the car model:

The automotive air conditioner adopts a stacked heat exchanger, which has good heat exchange effect and high heat exchange efficiency, and is energy-saving and environmentally friendly. The structural diagram of the entire refrigeration system below:

Internship experience: After the teacher's explanation of the car air conditioner, we have a new understanding of the car air conditioner, laying the foundation for the research, design and development of the car air conditioner.

Six: Xinfei Air Conditioning 2 visits internship

On September 15th, under the leadership of Teacher Wang Hong, we came to Henan Xinfei Air Conditioning Co., Ltd. to visit the internship. The first is the main process of production:

Fastening press pipe connection welding welding

Welding, welding, temperature control line, filling, sealing welding

Power on line power on test power on repair

Then there is the refrigerant circulation process: the temperature controller contacts the compressor to operate, the gaseous refrigerant is compressed into a high-pressure gas, and the heat is released into the condenser, and the heat is removed through the filter. The capillary is depressurized into a low-pressure liquid and enters the evaporator to absorb a large amount of heat at a low pressure. The refrigerant refrigerant sucked in by the refrigerant is sucked back by the compressor through the low pressure suction pipe. When the temperature in the tank drops to the required temperature, the temperature controller shrinks, the contact opens, the compressor stops rotating, and the temperature rises inside the box. When the temperature is high, the temperature control contact is closed, the compressor starts to work, and the refrigerant starts to circulate and cool.

Finally, the engineer explained the production capacity of the new Freezer 2: 3,600 units per day, each of which must be processed through at least XX processes.

Seven: Xuepu Refrigeration Co., Ltd. visited the internship

Under the leadership of Mr. Wang, we came to Xuepu Refrigeration Co., Ltd., which is a small enterprise founded in recent years. It is mainly engaged in the production of engineering vehicle air conditioners. The company has shearing machines, bending machines, punching machines, copper pipe welding equipment, leak detection equipment, air conditioning assembly equipment, etc. In the engineer's explanation project, it mainly introduces the whole process of air conditioners they produce, the role of various components of air conditioners. The working principle and the sales of their suppliers and products. Let me introduce the production process of the evaporator and condenser core:

Side panel drawing technician under punching and flanging

drawing

Brass and fin drawings, blanking as required, copper tube bending, copper tube shrinkage

Cleaning the inner cavity, welding the shaped tube, expanding the tube, wearing the copper tube

Leak test finished product

These are some of the basic evaporator and condenser core production knowledge I learned from Snow Purchasing, which laid the foundation for my future design in the refrigeration industry.

Eight: Construction site of the outpatient building of the Second Affiliated Hospital of Xinxiang Medical College:

On the morning of September 21, we came to the construction site of the outpatient building of the Second Affiliated Hospital of Xinxiang Medical College in Weihui City. First of all, Mr. Wang stressed that it is necessary to pay attention to personal safety when entering the construction site, and to build the central air-conditioning construction that you have learned. The actual construction is combined.

Manager Zhang first took us to the second floor of the basement. The first thing I saw was the rectangular duct. The thickness of the duct was 1mm. The duct was welded with angle light. The connection of the duct was flanged. . Inside is the screw refrigeration compressor unit being installed. The compressor unit is produced in York. I only saw the nameplate of the oil separator: v=1.08m2, the refrigerant is r22 and r134a, and the design temperature is 125°C. The pump is Vertical single-stage prohibition pump, its nameplate: flow: 200/h, head: 32m, the necessary NPSH is 3.5m, the matching motor power is 30kw, r=1480r/min. After the introduction of Manager Zhang, we On the second floor, the second floor is the installed air duct. I will introduce a room as an example:

There is also a smoke exhaust pipe arrangement, but it has not been installed yet. The nameplate of the smoke exhauster: air volume 45180/h, speed r=700 r/min, wind pressure=542pa, power=1835kw, which I saw on the second floor. And some of the knowledge I learned, then I went to the top of the building to visit, because the roof is under construction, we went straight to the hall. The internship was successfully completed.

Internship experience: Through this internship tour of the Weihui site, I learned the role of central air conditioning in the building, the basic installation process of central air conditioning in the building and the piping design, layout and orientation of the system, for the future participation in construction A good bedding.

Nine: Disassembly and assembly of refrigeration units in family hospitals

On September 23, Mr. Wang Hong took us to the factory of the machine expert institute to disassemble the refrigeration unit.

The first is the classification of compressors:

According to the principle of action: volumetric and speed. The volumetric formula is divided into: reciprocating, rotary, and screw. Today we are disassembling the crank-link compressor. The piston-cooling compressor often uses the crank-link mechanism. Its components are as follows: the body, the transmission mechanism, and the valve train.

The following is the name of the piston compressor:

Number of cylinders + type of working fluid + cylinder distribution form + cylinder diameter + sealing structure

6fw7b----The number of cylinders is 6, the working fluid is freon, the cylinder distribution is w-type, the cylinder diameter is 70mm, semi-closed structure.

2f10----The number of cylinders is 2, the working fluid is freon, the cylinder distribution is v-shaped, the cylinder diameter is 100mm, and the open structure.

In addition, for the semi-hermetic compressor, the motor cooling type uses the refrigerant vapor to recover heat.

Ten: Teacher Hou explained the construction of central air conditioning

On September 24, Teacher Hou gave us a construction report on central air conditioning.

Mr. Hou explained from the most basic construction: construction overview, construction technology, construction quality, design instructions, etc.

1, preparation instructions

2. Project Overview

3. Preparation of construction organization plan

4. Determination of construction plan and preparation of construction technology

Labor plan construction equipment entry plan

Construction, technical, and material preparation for the design of the construction organization

5. Quality control objectives and assurance measures

Technical guarantee measures personnel material operation level special equipment

6, the basic principles of installation

Beautiful reserved maintenance space operation is convenient horizontal and vertical, straight angle

7. Duration guarantee measures

Technically guaranteed labor plan progress plan, including weekly, monthly, quarterly, annual personnel management materials supply

8. Construction cooperation

9. Safe and civilized production measures

10, finished product protection

11, commissioning, the overall test

12, delivery acceptance, data assessment

Eleven: Carnival ktv central air conditioning internship visit

The central air conditioner of the carnival is the module unit whose drawings are as follows:

Internship experience

After three weeks of internships, I learned a lot and gained a lot. From the piston refrigeration unit, the screw refrigeration unit, the centrifugal refrigeration unit, the absorption refrigeration system to the understanding of the automobile air conditioner, the understanding of the module unit, the production process of the freezer, the disassembly and assembly of the compressor, and the construction of the central air conditioner. In the middle, I combined the knowledge I have learned with the actual production, work and life, and found that there are still many aspects that are very weak. I need to strengthen my practical ability and study. Only in this way can I learn and use, theory and practice. Combine them to achieve the purpose of learning and use, and lay the foundation for moving to work in the future.

I would also like to thank the three teachers Li Jianxiong, Wang Hong, and Li Haoxue for their guidance and care in all aspects of my internship during the internship process, as well as helping me solve difficult problems. Classmates, sincerely say to you: "You have worked hard, thank you."