HEAT TRANSFER TERMINOLOGY

Heat Transfer HEAT TRANSFER TERMINOLOGY HEAT TRANSFER TERMINOLOGY To understand and communicate in the thermal science field, certain terms and expressions must be learned in heat transfer. EO 1.1 DESCRIBE the difference between heat and temperature. EO 1.2 DESCRIBE the difference between heat and work. EO 1.3 DESCRIBE the Second Law of Thermodynamics and how it relates to heat transfer. EO 1.4 DESCRIBE the three modes of heat transfer. EO 1.5 DEFINE the following terms as they relate to heat transfer: a. Heat flux b. Thermal conductivity c. Log mean temperature difference d. Convective heat transfer coefficient e. Overall heat transfer coefficient f. Bulk temperature Heat and Temperature In describing heat transfer problems, students often make the mistake of interchangeably using the terms heat and temperature. Actually, there is a distinct difference between the two. Temperature is a measure of the amount of energy possessed by the molecules of a substance. It is a relative measure of how hot or cold a substance is and can be used to predict the direction of heat transfer. The symbol for temperature is T. The common scales for measuring temperature are the Fahrenheit, Rankine, Celsius, and Kelvin temperature scales. Heat is energy in transit. The transfer of energy as heat occurs at the molecular level as a result of a temperature difference. Heat is capable of being transmitted through solids and fluids by conduction, through fluids by convection, and through empty space by radiation. The symbol for heat is Q. Common units for measuring heat are the British Thermal Unit (Btu) in the English system of units and the calorie in the SI system (International System of Units). Rev. 0 Page 1 HT-02