[L1] 1 Steam Diagram (T-v Diagram) [c] T-v Diagram [c] P-v Diagram [L1] 2 State Analysis [L2] 1) Sensible Heat (Liquid Heat 1→2) [L4] - Heat involved only in the temperature change of a substance (sensible heat) [L4] - The extent of a substance's temperature change depends on its inherent specific heat. [L4] - Related State Variables [L5] * Δq = dh - vdp [L5] * 1q2 = h2 - h1 [L2] 2) Latent Heat (Evaporation Heat 2→3) [L4] - Heat involved only in the phase change of water [L4] - The term 'latent heat' is also expressed as 'hidden heat' (latent heat). [L4] - It does not change the temperature of the substance. [L4] - Among the heat transferred from the Earth's surface to the atmosphere as part of Earth's radiative energy, latent heat from evaporation/condensation is greater than sensible heat from convection. [L4] - At atmospheric pressure, the amount of latent heat is higher than sensible heat, but as pressure increases, the amount of sensible heat increases. [L2] 3) Sensible Heat (Superheated Steam 3→4) [L4] - Saturated steam (dry steam) is generated when heated to its boiling point (sensible heating) and when vaporized by additional heat (latent heating). When steam is heated above its boiling point, it becomes superheated steam (sensible heating). [L5] * State of quality 1 [L5] * When heating a boiler, steam is generated, and this steam contains unvaporized water molecules (wet steam). It is difficult to create perfectly superheated steam (saturated steam). [L5] * Used for propulsion/driving purposes such as turbines, and not for heat transfer applications. [L5] * Features fast and uniform heating using latent heat, temperature control possible through pressure, and a high heat transfer coefficient. [L4] - Superheated steam is generated by further heating wet steam or saturated steam above its saturation temperature. Steam with a higher temperature and lower density than saturated steam is produced. [L5] * During normal operation in a power plant, condensate does not form within steam-driven devices, eliminating the risk of erosion or corrosion. [L5] * Due to disadvantages such as a low heat transfer coefficient, variable steam temperature at constant pressure, and the use of sensible heat for heat transfer, saturated steam is used more in industry than superheated steam. [L4] - Supercritical water: Water in a state exceeding the critical point, corresponding to 22.1 MPa and 374℃.