Metamorphic rock Metamorphic rock Metamorphic rocks arise from the transformation of existing rock types, in a process called metamorphism, which means "change in form". The original rock (protolith) is subjected to heat (temperatures greater than 150 to 200 °C) and pressure ( or more), causing profound physical or chemical change. The protolith may be a sedimentary, igneous, or existing metamorphic rock. Metamorphic rocks make up a large part of the Earth's crust and form 12% of the Earth's land surface. They are classified by texture and by chemical and mineral assemblage (metamorphic facies). They may be formed simply by being deep beneath
Nuclear reactor heat removal thermal transfer crisis characterized by a sudden decrease in the transfer coefficient due to the presence of only one-phase transfer. The heat transfer coefficient in the pre-crisis period can be determined from the relationship: formula_55 where formula_56 In these formulas the following notations were made: formula_57 is pressure losses for the two phases (water and vapors), formula_58 ( formula_20 - the thermal flux, formula_60- the enthalpy of the biphasic liquid-gaseous mixture). The heat transfer coefficient during the crisis is related to the critical heat flow formula_61 through a linear relationship, of the equation type formula_19 that was presented before: formula_63