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Vapor-compression refrigeration [6] For comparison, a simple stylized diagram of a heat pump's vapor-compression refrigeration cycle: 1) condenser, 2) expansion valve, 3) evaporator, 4) compressor (Note that this diagram is flipped vertically and horizontally compared to the previous one) [7] Temperature–entropy diagram of the vapor-compression cycle.
diagram of a double-effect falling film evaporator. Condensing vapors from flash tank B1 heat evaporator A2. •1=feed •2=product •3=steam •4=vapors. In chemical engineering, a multiple-effect evaporator is an apparatus for efficiently using the heat from steam to evaporate water. [1]
The evaporator is where the circulating refrigerant absorbs and removes heat which is subsequently rejected in the condenser and transferred elsewhere by the water or air used in the condenser. To complete the refrigeration cycle, the refrigerant vapor from the evaporator is again a saturated vapor and is routed back into the compressor.
Evaporator : The refrigerant liquid moves from the condenser in the upper shell down to the evaporator in the lower shell and is sprayed over the evaporator tube bundle. Due to the extreme vacuum of the lower shell [6 mm Hg (0.8 kPa) absolute pressure], the refrigerant liquid boils at approximately 39 °F (4 °C), creating the refrigerant effect.
A multi-evaporator system is a vapor-compression refrigeration system generally consisting of four major components: Evaporator; Compressor; Condenser; Thermal expansion valve; Sometimes in a refrigerator several loads are varied. Refrigerators used to function at different loads operated under different condition of temperatures and pressures.
When stated in terms of temperature differences, Newton's law (with several further simplifying assumptions, such as a low Biot number and a temperature-independent heat capacity) results in a simple differential equation expressing temperature-difference as a function of time. The solution to that equation describes an exponential decrease of ...
Use a psychrometric chart to calculate wet bulb temperature, and then add 5–7 °F as described above. Use a rule of thumb which estimates that the wet bulb temperature is approximately equal to the ambient temperature, minus one third of the difference between the ambient temperature and the dew point. As before, add 5–7 °F as described above.
The number of transfer units (NTU) method is used to calculate the rate of heat transfer in heat exchangers (especially parallel flow, counter current, and cross-flow exchangers) when there is insufficient information to calculate the log mean temperature difference (LMTD). Alternatively, this method is useful for determining the expected heat ...