Calculations can be performed by assuming an isenthalpic
evolution (h = cost) through this path.
Among the methods of environment climatization for lactating sows, the localized cooling presents the advantage of reducing air temperature through isenthalpic
process, using the cession of sensible heath of the air in contact with the liquid surface (Tolon & Naas, 2005), triggering the mechanism of thermal change through convection.
Flash evaporation of single-component liquid is an isenthalpic
This positive relationship can be attributed to Joule-Thomson effect ([([partial derivative]T/[partial derivative]P).sub.H]), which defines change in temperature during (de)compression of C[O.sub.2] based on its counterpart of pressure change under the isenthalpic
Complementary equations were used to solve the system of equations, which required some assumptions to be made: 1) the system operates in the steady state, with mass conservation; 2) pressure drops in the pipes were considered as negligible; 3) the contribution of kinetic and potential energies were considered as negligible in all control volumes; 4) heat exchanges to the surroundings were considered very low for all components, except in COND and AHEA; 5) expansions in pressure reducing valves were considered isenthalpic
; 6) material flows entering and leaving the apparatus were considered as being one-dimensional.
* The expansion valve undergoes an isenthalpic
Vapor compression cooling cycles deviate from the Carnot refrigeration cycle in several ways, such as isenthalpic
expansion of saturated liquid at the condenser outlet and desuperheating of refrigerant vapor at the compressor outlet.
Therefore, when the assumption of the isenthalpic
flow through the valve holds true, the specific enthalpy of the gas transferred between the volumes depends on the flow direction, and it is equal to
Table 1 shows that steam pressure reduction through a PRV from 140 psig (965 kPa) to 20 psig (138 kPa) is an isenthalpic
process that maintains a constant enthalpy through the pressure reduction.
Furthermore, it was assumed that only saturated liquid and saturated vapor exit the receiver, the isentropic efficiency of the low-pressure, high pressure and bypass compressors was 0.65 and the expansion valves were isenthalpic
. Finally, the thermodynamic properties of the refrigerants were determined using the National Institute of Standards and Technology (NIST) Reference Fluid Thermodynamic and Transport Properties Database (REFPROP) Version 8.0 (Lemmon et al., 2007).
All systems depend on gas expansion, either (a) isenthalpic
(Joule-Thomson) with no work removal, or (b) one of the systems utilizing work extraction to reduce the energy content and therefore the temperature of the gas.