Related Experiment Video
Updated: May 26, 2026
07:32
Pool-Boiling Heat-Transfer Enhancement on Cylindrical Surfaces with Hybrid Wettable Patterns
Published on: April 10, 2017
Heat can cool near-critical fluids
Daniel Beysens1, Thomas Fröhlich, Yves Garrabos
1ESEME, Laboratoire de Physique et Mécanique des Milieux Hétérogènes, UMR CNRS-ESPCI ParisTech, Université Paris 6-7, Paris, France. daniel.beysens@espci.fr
Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics
|December 21, 2011
Summary
Experiments with compressible fluids near the critical point reveal anomalous cooling. This phenomenon, observed under microgravity and Earth
Area of Science:
- Thermodynamics
- Fluid Dynamics
- Critical Phenomena
Background:
- Understanding fluid behavior near the liquid-gas critical point is crucial for various physical and chemical processes.
- Gravity significantly influences heat and mass transfer in fluids, especially near critical points.
Purpose of the Study:
- To investigate heat transfer dynamics in highly compressible fluids under varying gravitational conditions.
- To explore the phenomenon of anomalous cooling in fluids near their critical point.
Main Methods:
- Experiments conducted using sulfur hexafluoride (SF6) under microgravity and carbon dioxide (CO2) under Earth's gravity.
- Utilized an interferometer cell with in-situ thermistors for temperature measurement and heat pulse generation.
- Analyzed temperature evolution governed by heat flux balance between boundary layers.
Main Results:
- Observed an unconventional, prolonged cooling effect where bulk fluid temperature dropped significantly below initial levels after heat pulses.
- This anomalous cooling is attributed to rapid fluid decompression driven by the disappearance of the hot boundary layer and a persistent cold boundary layer.
- The effect is more pronounced under higher gravitational acceleration and persists until the cold boundary layer diffuses.
Conclusions:
- The study demonstrates a novel anomalous cooling phenomenon in compressible fluids near the critical point.
- This effect is strongly influenced by gravity-induced convection and boundary layer dynamics.
- Findings provide insights into heat transfer mechanisms in critical fluids, relevant for space and terrestrial applications.
Related Concept Videos
02:44Heating and Cooling Curves
When a substance—isolated from its environment—is subjected to heat changes, corresponding changes in temperature and phase of the substance is observed; this is graphically represented by heating and cooling curves.
For instance, the addition of heat raises the temperature of a solid; the amount of heat absorbed depends on the heat capacity of the solid (q = mcsolidΔT). According to thermochemistry, the relation between the amount of heat absorbed or released by a substance, q, and its...
For instance, the addition of heat raises the temperature of a solid; the amount of heat absorbed depends on the heat capacity of the solid (q = mcsolidΔT). According to thermochemistry, the relation between the amount of heat absorbed or released by a substance, q, and its...
01:11Temperature and Thermal Equilibrium
Heat and temperature are essential concepts for everyone every day. The study of heat and temperature is part of an area of physics known as thermodynamics. It is not always easy to distinguish heat and temperature.
The concept of temperature has evolved from the common concepts of hot and cold. The scientific definition of temperature explains more than just our sense of hot and cold. Temperature is operationally defined as the quantity measured with a thermometer. Furthermore, temperature is...
The concept of temperature has evolved from the common concepts of hot and cold. The scientific definition of temperature explains more than just our sense of hot and cold. Temperature is operationally defined as the quantity measured with a thermometer. Furthermore, temperature is...
01:12Heat Flow and Specific Heat
Heat is a type of energy transfer that is caused by a temperature difference, and it can change the temperature of an object. Since heat is a form of energy, its SI unit is the joule (J). Another common unit of energy often used for heat is the calorie (cal), which is defined as the energy needed to change the temperature of 1 g of water by 1 °C, specifically between 14.5 °C and 15.5 °C, since the energy needed shows a slight temperature dependence. Another commonly used unit is the kilocalorie...
01:22Methods of reducing fever
The signs and symptoms of fever include hot and dry skin, flushed face, thirst, muscle aches, anorexia, headache, tachycardia, tachypnea, and fatigue. Elevated body temperature is reduced using two methods: pharmacological and nonpharmacological. Proper identification and treatment of the root cause of a fever is of utmost importance.
Pharmacological Methods of Reducing Fever:
Pharmacological Methods of Reducing Fever:
01:14Mechanisms of Heat Transfer
Heat transfer between the human body and its environment occurs through four main mechanisms: conduction, convection, radiation, and evaporation.
Conduction, accounting for approximately 3% of body heat loss at rest, is the process of exchanging heat between molecules of two materials in direct contact. This can result in both heat loss and gain. For instance, when the body is submerged in water, which conducts heat 20 times more effectively than air, it can either lose or gain significant heat.
Conduction, accounting for approximately 3% of body heat loss at rest, is the process of exchanging heat between molecules of two materials in direct contact. This can result in both heat loss and gain. For instance, when the body is submerged in water, which conducts heat 20 times more effectively than air, it can either lose or gain significant heat.
01:19Mechanism of heat transfer
Understanding heat transfer mechanisms is essential for understanding how our bodies maintain balance in different environmental conditions. When the environment is thermoneutral, the body is in a state of balance, neither using nor releasing energy to maintain its core temperature. However, when the environment is not thermoneutral, the body employs four heat transfer mechanisms to maintain homeostasis: conduction, convection, evaporation, and radiation. These mechanisms facilitate heat...