Abstract. The combustion chamber constitutes a crucial component of a liquid rocket engine (LPRE), and approximately 30% of serial engine failures are attributed to issues within it. Primarily, challenges encountered during engine chamber operation stem from the inadequacy of the current cooling systems to manage thermal loads effectively. These loads, unique to liquid-propellant rocket engine chambers, result of high pressures, temperatures, and flow rates of dissociating combustion products. Regenerative cooling stands as the primary method to safe the chamber walls from overheating and subsequent deterioration. Other methods serve as supplementary measures, often utilized in conjunction with regenerative cooling (e.g., internal film cooling), or are tailored to specific applications, such as radiation cooling of upper-stage engine nozzles. However, the advancement of heat transfer theory within liquid-propellant rocket engine chambers has been relatively stagnant, with widely accepted calculation methods established as far back as the 1970s. Consequently, these methods fail to harness the considerable computing power enhancements since their inception, neglect new experimental data, and lack adaptation to modern engine manufacturing technologies like 3D printing. Concurrently, the burgeoning number of startups in the rocket and space sector, constrained by limited budgets, necessitates the swift development of viable designs without extensive and costly testing. Hence, the need for validated calculation methods for regenerative cooling is paramount. This study endeavors to address this need by formulating a system of differential equations, grounded on the mass, momentum, and energy conservation laws, to describe the processes within the cooling circuit of the liquid-propellant rocket engine chamber. Additionally, the model is dimensionally reduced for simplification. Comparative analysis against established engineering methodologies showcases the advantages of the proposed approach, underscoring its potential for enhancing cooling system design efficacy.