Analysis of heat transfer performance of commonly used mid deep coaxial sleeve deep well heat exchangers

Analysis of heat transfer performance of commonly used mid deep coaxial sleeve deep well heat exchangers

Abstract: This article aims to analyze in depth the heat transfer performance of deep well heat exchangers with deep and shallow coaxial casing. Through theoretical analysis and experimental research, the heat transfer mechanism, influencing factors, and optimization strategies of the heat exchanger were explored. The results indicate that the deep and shallow coaxial casing type deep well heat exchanger has high heat transfer efficiency, and its performance is influenced by factors such as depth of field, casing structure, and fluid properties. Optimizing the casing structure, increasing fluid flow rate and temperature difference can further enhance its heat transfer performance.

Keywords: deep well heat exchanger; Coaxial sleeve; Heat transfer performance; Heat transfer mechanism; influencing factors

1. Introduction

With the increasing demand for energy and the strengthening of environmental awareness, efficient and energy-saving heat exchange technologies have been widely applied in many fields. As an efficient and energy-saving heat exchange equipment, the deep well heat exchanger with deep and shallow coaxial casing has the advantages of compact structure, small footprint, and high heat transfer efficiency. Therefore, it has been widely used in fields such as petroleum, chemical, and geothermal energy. However, the heat transfer performance of the heat exchanger is affected by various factors, and how to optimize its performance has become a current research hotspot.

2、 Heat transfer mechanism of deep well heat exchanger with deep and shallow coaxial casing

The deep and shallow coaxial casing type deep well heat exchanger utilizes the constant temperature characteristics of deep underground layers to achieve heat transfer by exchanging heat between the fluid inside the casing and the underground rock and soil. The heat transfer process mainly includes two processes: convective heat transfer and thermal conduction heat transfer. Convective heat transfer occurs between the fluid inside the casing and the casing wall, while thermal heat transfer occurs between the casing wall and the surrounding rock and soil. The heat transfer efficiency of these two processes directly affects the performance of the entire heat exchanger.

3、 Analysis of influencing factors

1. The influence of depth of field: Depth of field is one of the important factors affecting the heat transfer performance of deep well heat exchangers. As the depth of field increases, the temperature of underground rock and soil becomes more stable, thereby improving the heat transfer efficiency of the heat exchanger. However, an increase in depth of field can also lead to increased construction difficulty and cost, so a balance needs to be made based on the actual situation.

2. The influence of casing structure: The structure of casing has a significant impact on heat transfer performance. A reasonable casing structure can increase the flow velocity and turbulence level of the fluid, thereby enhancing convective heat transfer. In addition, the thermal conductivity of the casing material also affects the heat transfer performance.

3. The influence of fluid properties: Fluid properties such as density, specific heat capacity, thermal conductivity, etc. are also important factors affecting heat transfer performance. The differences in these physical parameters can lead to variations in the heat transfer of fluids inside the casing.

4、 Optimization strategy

In order to improve the heat transfer performance of deep and shallow coaxial casing deep well heat exchangers, the following optimization strategies can be adopted:

1. Optimize the casing structure: By changing the casing structure, such as increasing the inner diameter of the casing, reducing the wall thickness, etc., the fluid velocity and turbulence can be increased, thereby enhancing convective heat transfer. At the same time, choosing materials with good thermal conductivity as casing materials can improve thermal conductivity and heat transfer efficiency.

2. Increase fluid velocity: Increasing the fluid velocity can improve the convective heat transfer coefficient, thereby enhancing heat transfer. In practical applications, fluid flow rate can be increased by increasing the power of the pump or optimizing the design of the fluid pipeline.

3. Increasing the temperature difference: Increasing the temperature difference between the fluid and the underground soil can improve heat transfer and thus enhance heat transfer efficiency. However, excessive temperature difference may lead to an increase in thermal stress of the casing material, so it needs to be comprehensively considered in practical applications.

5、 Experimental research

In order to verify the accuracy of theoretical analysis and further optimize the performance of the heat exchanger, we conducted experimental research. The heat transfer performance of the heat exchanger was tested under different depths of field, casing structures, and fluid properties in the experiment. The experimental results indicate that depth of field, casing structure, and fluid properties have a significant impact on heat transfer performance. After optimizing the casing structure and increasing the fluid flow rate, the heat transfer efficiency of the heat exchanger has been significantly improved.

VI. Conclusion

This article conducts theoretical analysis and experimental research on the heat transfer mechanism and influencing factors of deep well heat exchangers with deep and shallow coaxial sleeves, and draws the following conclusions:

Deep and shallow coaxial casing deep well heat exchangers have high heat transfer efficiency and are used in various application scenarios.

Depth of field, casing structure, and fluid properties are important factors affecting the performance of heat exchangers. Reasonable depth of field selection, optimized casing structure, and appropriate fluid properties can improve the heat transfer efficiency of the heat exchanger.

By optimizing the casing structure, increasing fluid flow rate, and widening the temperature difference, the performance of deep and shallow coaxial casing deep well heat exchangers can be further improved.

In future research, we will further explore the optimization design and operation strategies of deep and shallow coaxial casing deep well heat exchangers in different application scenarios, providing more reliable guidance for practical applications.