lämpöhyötys

Lämpöhyötys, or thermal efficiency, is a measure of how effectively a process converts thermal energy into useful work. It is a fundamental concept in thermodynamics and is particularly relevant in the study of heat engines, power plants, and various industrial processes. The term originates from Finnish, where "lämpö" means heat and "hyötys" means efficiency or utility.

Thermal efficiency is typically expressed as a dimensionless ratio or a percentage. It is calculated by dividing the amount of useful work produced by the amount of heat energy input. For example, if a heat engine consumes 100 joules of heat and produces 30 joules of work, its thermal efficiency is 30/100, or 30%. The remaining energy is lost, usually as waste heat.

The maximum possible thermal efficiency for any heat engine operating between two temperature reservoirs is given by the Carnot efficiency, which depends solely on the temperatures of the hot and cold reservoirs. Real-world engines are subject to various irreversibilities, such as friction and heat loss, which cause their actual thermal efficiency to be lower than the Carnot efficiency. Improving thermal efficiency is a key goal in engineering to reduce fuel consumption, minimize environmental impact, and increase the overall economic viability of energy conversion systems.