Lecture

Heat Transfer: Latent Heat and Enthalpy

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In course

PHYS-118: Building physics

Ce cours traite des principaux phénomènes physiques observables dans le bâtiment et doit permettre à l'étudiant d'acquérir des connaissances de base dans le domaine de la physique du bâtiment. ...

Description

This lecture covers the concepts of latent heat and enthalpy in the context of heat transfer. It explains how the overall heat content of humid air is linked to changes of state, particularly evaporation. The instructor discusses the importance of latent heat in processes like evaporation and how it affects the heat content of moist air. The lecture also delves into the role of sensible heat and water evaporation in determining the heat content of humid air. Various factors influencing thermal comfort, such as air temperature, relative humidity, and clothing, are explored in detail, along with mechanisms like radiation, air speed, and sweat production.

Instructors (2)

Jean-Louis Scartezzini

Director of EPFL Solar Energy and Building Physics Laboratory (1994-present); Founder & Director of ENAC Institute of Infrastructures, Resources and Environment (2002-2009); Founder & Director of EPFL Doctoral Program in Environment (2002-2009); Co-Director of EPFL Institute of Building Technology (1994-1997); Associate Professor of Building Physics at EPFL (1994-1997); Associate Professor of Building Physics at University of Geneva (1990-1997); Group Leader & Research Fellow at the EPFL Solar Energy Research Group (1981-1989); Research Fellow at the Applied Geophysics Institute of University of Lausanne (1980-1981).

Andreas Schueler

Studies of Physics at the University of Freiburg, Germany
Master of Science (Physics) from the University of Michigan, Ann Arbor, USA
PhD degree from the University of Basel, Switzerland

Official source

Ontological neighbourhood

Mechanical engineering

Thermal engineering: Air conditioning

Related concepts (32)

Heat transfer

Heat transfer is a discipline of thermal engineering that concerns the generation, use, conversion, and exchange of thermal energy (heat) between physical systems. Heat transfer is classified into various mechanisms, such as thermal conduction, thermal convection, thermal radiation, and transfer of energy by phase changes. Engineers also consider the transfer of mass of differing chemical species (mass transfer in the form of advection), either cold or hot, to achieve heat transfer.

Heat

In thermodynamics, heat is the thermal energy transferred between systems due to a temperature difference. In colloquial use, heat sometimes refers to thermal energy itself. An example of formal vs. informal usage may be obtained from the right-hand photo, in which the metal bar is "conducting heat" from its hot end to its cold end, but if the metal bar is considered a thermodynamic system, then the energy flowing within the metal bar is called internal energy, not heat.

Enthalpy of fusion

In thermodynamics, the enthalpy of fusion of a substance, also known as (latent) heat of fusion, is the change in its enthalpy resulting from providing energy, typically heat, to a specific quantity of the substance to change its state from a solid to a liquid, at constant pressure. It is the amount of energy required to convert one mole of solid into liquid. For example, when melting 1 kg of ice (at 0 °C under a ), 333.55 kJ of energy is absorbed with no temperature change.

Enthalpy of vaporization

In thermodynamics, the enthalpy of vaporization (symbol ∆Hvap), also known as the (latent) heat of vaporization or heat of evaporation, is the amount of energy (enthalpy) that must be added to a liquid substance to transform a quantity of that substance into a gas. The enthalpy of vaporization is a function of the pressure at which the transformation (vaporization or evaporation) takes place. The enthalpy of vaporization is often quoted for the normal boiling temperature of the substance.

Heat recovery ventilation

Heat recovery ventilation (HRV), also known as mechanical ventilation heat recovery (MVHR), is an energy recovery ventilation system that operates between two air sources at different temperatures. It's a method that is used to reduce the heating and cooling demands of buildings. By recovering the residual heat in the exhaust gas, the fresh air introduced into the air conditioning system is preheated (or pre-cooled), and the fresh air's enthalpy is reduced before it enters the room, or the air cooler of the air conditioning unit performs heat and moisture treatment.

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