[Paper Review] Heat Transfer and Cooling Techniques at Low Temperature

Bertrand Baudouy|arXiv (Cornell University)|Jan 1, 2014

Heat Transfer and Optimization11 references18 citations

TL;DR

This paper provides a comprehensive review of heat transfer mechanisms and cooling techniques applicable at cryogenic temperatures, covering conduction, convection, and radiation with material-specific data. It details practical cooling methods—from liquid bath cooling to cryocoolers and flow-based systems—offering design guidelines for efficient thermal management in superconducting accelerator systems, with key insights on thermal contact resistance and heat transfer correlations in low-temperature environments.

ABSTRACT

The first part of this chapter gives an introduction to heat transfer and cooling techniques at low temperature. We review the fundamental laws of heat transfer (conduction, convection and radiation) and give useful data specific to cryogenic conditions (thermal contact resistance, total emissivity of materials and heat transfer correlation in forced or boiling flow for example) used in the design of cooling systems. In the second part, we review the main cooling techniques at low temperature, with or without cryogen, from the simplest ones (bath cooling) to the ones involving the use of cryocoolers without forgetting the cooling flow techniques.

Motivation & Objective

• To provide a foundational understanding of heat transfer mechanisms at low temperatures, including conduction, convection, and radiation.
• To compile essential material-specific data for cryogenic applications, such as thermal contact resistance and total emissivity.
• To evaluate and compare cooling techniques used in low-temperature systems, both with and without cryogens.
• To support the design of efficient thermal management systems in superconducting accelerator technology.
• To offer practical design correlations for forced and boiling flow heat transfer in cryogenic conditions.

Proposed method

• Review of fundamental laws of heat transfer: Fourier's law for conduction, Newton's law of cooling for convection, and Stefan-Boltzmann law for radiation.
• Compilation of experimental data on thermal contact resistance between dissimilar materials at cryogenic temperatures.
• Presentation of total emissivity values for common engineering materials at low temperatures.
• Analysis of heat transfer correlations in forced flow and boiling conditions, including nucleate boiling and flow boiling regimes.
• Description of cooling techniques: liquid helium bath cooling, cryocooler-based systems, and cooling flow techniques using cryogenic fluids.
• Integration of these principles into practical design guidelines for cryogenic systems in particle accelerators.

Experimental results

Research questions

• RQ1 How do conduction, convection, and radiation mechanisms behave under cryogenic conditions?
• RQ2 What are the dominant thermal contact resistances between materials at low temperatures, and how can they be minimized?
• RQ3 How do heat transfer coefficients vary in forced and boiling flows at cryogenic temperatures?
• RQ4 What are the relative advantages and limitations of different cooling techniques, including cryocoolers and liquid cryogen baths?
• RQ5 What design correlations and material properties are essential for reliable thermal system performance in superconducting accelerators?

Key findings

• Thermal contact resistance between materials at cryogenic temperatures can be significantly higher than at room temperature, necessitating careful interface treatment.
• Total emissivity of common materials such as aluminum and stainless steel increases at low temperatures, enhancing radiative heat transfer.
• Heat transfer coefficients in boiling flows at cryogenic conditions can exceed those in single-phase forced flow by orders of magnitude, especially in nucleate boiling regimes.
• Cryocoolers enable continuous cooling without cryogen consumption, making them suitable for long-term operation in accelerator systems.
• Design correlations for forced and boiling flow heat transfer are essential for accurate prediction of system performance and thermal stability.
• The integration of accurate thermal data and appropriate cooling techniques is critical for minimizing heat loads in superconducting accelerator components.