Heat Exchanger and Heat Pump

Thermodynamics is an exciting and fascinating subject that deals with energy and energy interactions. Heat transfer is a basic science that deals with the rate of transfer of thermal energy in various media. This module is designed to give students a basic understanding of the laws of thermodynamics and the principles of heat transfer, leading to analyse of thermal engine cycles and design of heat exchangers. The module introduces the concepts of heat, work, reversibility, efficiency and property diagrams of pure substance while discussing the 1st law of thermodynamics. The ideal-gas equation of state is introduced for ideal gases while real gases are described by other polytropic models. The 2nd law of thermodynamics introduces the efficiency calculation for the heat engine and refrigeration/heat pump cycle, which these thermodynamic cycles can be approximated by an idealised reversible Carnot cycle. The 3rd law of thermodynamics set the stage for the discussion of the actual vapour power cycle (Rankine) and actual vapour- compression refrigeration cycle.

In heat transfer, three main mechanisms of heat flow will be discussed; conduction, convection and radiation. Conduction introduces Fourier’s law with an emphasis on developing 1D heat transfer in steady-state condition for various structures. There are two modes of convection, namely natural and forced convection, where some convection correlations are derived to demonstrate and allow appreciation of its respective empirical convection heat transfer coefficient in the real world. Conduction and convection are re-visited again in the heat exchanger topic where design issues and the concept of Log Mean temperature Difference (LMTD), Number of Transfer Units (NTU) method are introduced. Overall, the module aims to develop an appreciation of the importance of thermal systems in sustainable infrastructures.

The topics covered in this module include:

• To describe the Laws of Thermodynamics in thermal systems
• To apply thermodynamics concepts to the understanding of heat pumps
• To discuss the property diagrams and P-v-T surface.
• To discuss the mechanisms of Heat Transfer; Conduction, Convection, and Radiation
• To analyse heat transfer problems
• To design a refrigerant cycle system in an assignment
• To assess various heat exchanger configurations and their maintenance issues