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Joule heating (also known as resistive, resistance, or Ohmic heating) is the process by which the passage of an electric current through a conductor produces heat.. Joule's first law (also just Joule's law), also known in countries of the former USSR as the Joule–Lenz law, [1] states that the power of heating generated by an electrical conductor equals the product of its resistance and the ...
Between 1840 and 1843, Joule carefully studied the heat produced by an electric current. From this study, he developed Joule's laws of heating, the first of which is commonly referred to as the Joule effect. Joule's first law expresses the relationship between heat generated in a conductor and current flow, resistance, and time. [1]
In a closed system (i.e. there is no transfer of matter into or out of the system), the first law states that the change in internal energy of the system (ΔU system) is equal to the difference between the heat supplied to the system (Q) and the work (W) done by the system on its surroundings.
The middle term is the Joule heating, and the last term includes both Peltier (at junction) and Thomson (in thermal gradient) effects. Combined with the Seebeck equation for J {\displaystyle \mathbf {J} } , this can be used to solve for the steady-state voltage and temperature profiles in a complicated system.
[13] [14] This type of systems is well coupled with cogeneration systems where both heat and electricity are produced. Depending on the configuration, the system can maximise heating and cooling production from a given amount of fuel, or can improve the temperature (hence the quality) of waste heat from other processes. [15]
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James Joule was born in 1818, the son of Benjamin Joule (1784–1858), a wealthy brewer, and his wife, Alice Prescott, on New Bailey Street in Salford. [3] Joule was tutored as a young man by the famous scientist John Dalton and was strongly influenced by chemist William Henry and Manchester engineers Peter Ewart and Eaton Hodgkinson.
Utilizing this large source of relatively moderate temperature earth, a heating or cooling system's capacity can often be significantly reduced. Although ground temperatures vary according to latitude, at 1.8 metres (6 ft) underground, temperatures generally only range from 7 to 24 °C (45 to 75 °F).