This chapter provides a comprehensive discussion on the integration of fluid dynamics, heat transfer engineering, and plasma engineering, disciplines that span the fields of mechanical engineering, chemical engineering, and electrical engineering. The chapter introduces a fundamental equation system for plasma heat transfer fluids and explores its key characteristics. In typical books, there is often a significant gap between fundamental theory and practical application. To bridge this divide, this chapter emphasizes an application-oriented perspective, ensuring that the concepts are presented in a manner relevant to real-world implementations. The derivation of fundamental equations and mathematical formulations is accompanied by practical examples related to plasma applications, facilitating a clearer understanding of their significance. Additionally, the mechanisms of heat transfer in both equilibrium and nonequilibrium plasmas are examined in detail. This discussion is structured around the fundamental equation system and includes concrete examples of computational analyses. The chapter concludes with a summary of key findings and a set of exercise problems to reinforce the concepts covered.