Building Envelope Part 1-MANSUR.pptx - Energy Management in Building Envelope Part 1 Heat Transfer Fundamentals niversity of Jordan UJ Outline

Building Envelope Part 1-MANSUR.pptx - Energy Management in...

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niversity of Jordan - UJ Energy Management in Building Envelope Part 1: Heat Transfer Fundamentals
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niversity of Jordan - UJ Outline Introduction to heat transfer concepts and principles. Heat transfer mechanisms: Conduction Convection Radiation Analysis of heat conduction in plane walls.
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niversity of Jordan - UJ Introduction to Heat Transfer Heat is the form of energy that can be transferred from one system to another as a result of temperature difference. The science of heat transfer deals with the determination of the rates of energy that can be transferred from one system to another as a result of temperature difference. The larger the temperature gradient, the higher the rate of heat transfer.
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niversity of Jordan - UJ Heat Transfer Problems Rating problems: Determination of the heat transfer rate for an existing system at a specified temperature difference. Sizing problems: Determination of the size of a system in order to transfer heat at a specified rate for a specified temperature difference. The solution of real-world heat transfer problems is primarily based on modeling using simple, but adequate models.
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niversity of Jordan - UJ Heat and Energy Heat is one form of energy (kinetic, potential, mechanical, electrical, magnetic, thermal, nuclear). The International unit of energy is Joule ( J ). Other units of energy are: British Thermal Unit (BTU): (1 BTU=1.055 kJ) Calorie: (1 Calorie = 4.187 J).
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niversity of Jordan - UJ Heat and Energy Internal Energy ( u ) is the sum of all forms of energy related to the molecular structure and the degree of molecular activity of a stationary system, consisting of: sensible energy (sensible heat): related to the kinetic energy of the molecules which is proportional to the temperature. latent energy (latent heat): related to the phase of the system. Enthalpy ( h ) is the sum of internal energy and flow energy of a moving fluid: h = u + Pv
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niversity of Jordan - UJ Specific Heats Specific heat is defined as: the energy required to raise the temperature of a unit mass of a substance by one degree. Two kinds of specific heats: specific heat at constant volume c v , specific heat at constant pressure c p The unit for specific heat is kJ/kg.K or kJ/kg. C In general, the specific heats of a substance depend on two independent properties such as temperature and pressure. However, for an ideal gas they depend on temperature only.
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niversity of Jordan - UJ Specific Heats U=m c v,avg T H=m c p,avg T The constant-volume and constant-pressure specific heats are identical for incompressible substances . The specific heats of incompressible substances depend on temperature only: U=m c avg T
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niversity of Jordan - UJ Energy Transfer Energy can be transferred to or from a given mass by two mechanisms: heat transfer work .
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