によって Shanon Reckinger 9年前.
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Multiple inlets and exits
Sum(mi)=Sum(me)
One inlet/ one exit
mdoti=mdote
Coefficient of Performance Actual COP, beta_ref=QL/W Carnot (ideal) COP, beta_ref=TL/(TH-TL)
Coefficient of Performance Actual COP, beta_hp=Qh/W Carnot (ideal) COP, beta_hp=Th/(Th-TL)
Thermal Efficiencies Actual Efficiency, \eta_he=W/Qh Carnot (ideal) Efficiency, \eta_he=1-TL/Th
Emptying/Filling a Tank
Single Inlet/Single Exit, se-si=\int q/T + sgen
Entropy Generation, sgen
Irreversible, sgen is positive
Reversible, sgen=0
Heat Transfer, \int q/T Can only calculate if you know how T changes through the device or process.
Adiabatic, \int q/T=0
Isothermal, \int q/T = q/T
Entropy change, calculate the same way as closed systems
Entropy Generation, Sgen
if irreversible, Sgen>0
Also if irreversible.... (S2-S1)=Q/Tsurr + Sgen (universe)
if reversible, Sgen=0
Heat transfer, \int delta Q/T
if isothermal, \int delta Q/T=Q/Tsystem
if adiabatic, \int delta Q/T=0
Entropy Change, s2-s1
Type of process
Process, s2-s1~=0
Cycle, s2-s1=0
Substance Types
solids and liquids (no phase change), s2-s1=C*ln(T2/T1)
ideal gas, (s2-s1)=Cp0*ln(T2/T1)-R*ln(P2/P1)
when phase changes, use tables
Work, W
Other (usually given or what you are finding)
Chemical
Electrical
Shaft
Boundary Work
When boundary is moving (volume changes through the process), W=\int P dV
Linear, P=mV+b
Polytropic, P=C/V^n
Isothermal (constant temperature) and ideal gas, P=mRT/V
Isobaric, constant pressure P=C
Heat, Q
Usually this is given or it is what you are finding
Types
Radiation
Convection
Conduction
Total Energy, \Delta E
Internal Energy, \Delta U
If Solid or Liquid (no phase change)
\Delta u=C*\Delta T
If multi phase (water, refrigerant, or ammonia)
Use tables
Superheated Vapor
P
Saturated Vapor
P=Psat T=Tsat u=ug (ditto for v, s, & h)
Saturated Mixture
P=Psat T=Tsat u=uf+x*ufg (ditto for v, s, & h)
Saturated Liquid
P=Psat T=Tsat u=uf (ditto for v, s, & h)
Compressed Liquid
P>Psat
T
If ideal Gas
\Delta u = C_v0*\Delta T
Kinetic Energy, \Delta KE
Potential Energy, \Delta PE
Transient Systems
Filling or Emptying a Tank
Steady Systems
Multiple Inlets/Exits
Mixing Chambers
Heat Exchanger
Single Inlet/Single Exit q+h_i+ke_i+pe_i=w+h_e+ke_e+pe_e
Pipes/Ducts
Heater/Cooler/Boiler
Pumps
Compressors/Fans
Turbines/Expanders
Throttling Devices/Valves
Nozzle/Diffuser