Compressor Work (Isentropic)
Compute the specific compression work in an ideal refrigeration cycle, W = h₂ − h₁, the enthalpy difference between the compressor outlet and inlet (isentropic compression, at constant entropy). It is the energy the compressor adds to the refrigerant per kilogram — the cycle's 'electricity bill'. Together with the refrigerating effect, it defines the COP (COP = refrigerating effect/work). Enter the outlet and inlet enthalpies.
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Trabalho do compressor (isentrópico)
No ciclo de refrigeração por compressão de vapor, o compressor é o coração — e o único componente que consome energia (a 'conta de luz' do sistema). Idealmente, a compressão é isentrópica (a entropia constante, sem perdas nem troca de calor), e o trabalho específico é simplesmente a diferença de entalpia: W = h₂ − h₁ (kJ/kg). Esse é o salto de energia que o vapor refrigerante recebe ao ser comprimido da pressão baixa do evaporador para a pressão alta do condensador. O trabalho do compressor é metade da história do COP: COP = efeito refrigerante / trabalho do compressor. Um ciclo eficiente maximiza o calor absorvido no evaporador (efeito refrigerante) e minimiza o trabalho gasto — daí a importância de não comprimir mais do que o necessário (razões de compressão moderadas) e de manter as diferenças de temperatura pequenas. Compressores reais têm eficiência isentrópica de 70–85%, gastando mais que o ideal. No diagrama pressão-entalpia (P-h), o trabalho é o segmento horizontal da linha de compressão. Informe as entalpias na saída e na entrada do compressor.
Related Tools
Carnot COP (Refrigeration)
Compute the maximum theoretical coefficient of performance (COP) of a refrigerator, COP = Tc/(Th − Tc), with temperatures in kelvin, where Tc is the cold-source (evaporator) temperature and Th the hot-source (condenser). It is the limit set by the 2nd law of thermodynamics: no real refrigerator can exceed it. The smaller the temperature difference between the sources, the higher the possible COP — which is why refrigerating to very low temperatures is so costly. Enter the cold and hot temperatures in kelvin.
Back Work Ratio (BWR)
Calculate the back work ratio (BWR) of a power cycle, BWR = w_compressor ÷ w_turbine, dividing the work consumed by the compressor (or pump) by the gross work produced by the turbine. The dimensionless result shows what fraction of turbine work is reinvested to compress the fluid. In gas turbines (Brayton cycle) the BWR is high (0.4–0.6), since compressing gas is costly; in steam Rankine cycles it is tiny (~0.01), since pumping liquid is cheap. A high BWR makes the cycle sensitive to component efficiencies. Enter the compressor work and the turbine work.
Superheat Degree
Compute the superheat of a refrigeration system, ΔT = T_suction − T_evaporation(saturation), how much hotter the refrigerant vapor is than its saturation temperature at the evaporator pressure. Proper superheat (typically 5–10 °C) ensures only vapor (no liquid) reaches the compressor, protecting it from liquid slugging. Too much superheat reduces capacity. It is controlled by the expansion valve. Enter the suction and saturated evaporation temperatures.
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