Me talking..to myself..again(DO NOT READ)
Cycles Suck so many to remember..
carnot otto diesel brayton(gas turbine) dual rankine refrigeration cycles... did I miss any?
Refrigeration cycle is a bit weird though it's like playing with mahjong in the wrong direction anti clockwise when all the other cycles flow clockwise and you're not used to the way the cycle flows.
A lot of freaking stuff to remember. like if it's vapour liquid mixture, have to find quality x via x = (v-vf)/(vfg) then find the respective u or h or s otherwise you'll get the wrong ans.
gas relations , only for isentropic processes. (T2/T1)= (P2/P1)^0.4/1.4=(V1/V2)^0.4~ideal gas otherwise PV/T=PV/T eh..
intrapolation sucks
I hope they give nice numbers, so dun have to intrapolate that much
Compressor work will have more so Wactual = Wc/nth<-----Compressor efficiency Pump work will have less so Wactual = (Wp)(nth)<----turbine efficiency dunnoe leh dunnoe wat will come out. Q1 They'll maybe ask us to prove a violation of clausius leads to a violation of the Kelvin- Plank statement. Instead of the other way round, maybe not. Then they'll ask on Clausius inequality.. Part 2 tiny Entropy question. Sin - Sout + Sgen = change in S
Ask you to find Sgen
Adiabetic: entropy by heat = 0
Closed system: entropy by mass=0
steady flow: change in S = 0
Reversible: Sgen =0
For solid/ liquid ==> change in s =mCavlnT2/T1
Q2 Part 1 on Energy balance on steady flow systems. or if they wanna make me work for it.. add Q in..
Ein - Eout = Change in energy --> min(h+ v^2/2) + Qin - mout(h+ v^2/2) = mu(ini) - mu(fin)
But most of the time KE and PE is assumed zero, unless they give u area of inlet or something. then KE is in.
if Steady flow,change in mass flow rate = 0. --> change in energy = 0 Ein=Eout
Mass flow rate = (VA/v) if just mass is (V/v) v is specific volume.
Part 2 Thermal energy reservoirs: 2 thermal reservoirs find --> COP --> heat rejection or something..
Carnot COP HP = 1/(1-Tl/Th) = Qh/Wnet ,Carnot COP R =1/(Tl/Th-1) = Ql/Wnet, efficiency HE = 1/COPhp = Wnet/Qh
Q3Cos last year it's Carnot and otto and last last yr it's gas and refrigeration. so you cancel out from the cycles and you left with Rankine cycle. maybe Reheat. plus work pump and turbine efficiency for kicks... find net work, find efficiency.. blah blah..
Q4 Diesel cycle then they'll throw in one sub question on partial pressure.
not very difficult if u say it like tat but when I see the question I'll totally forget how to do.. I hope i remember.............
I'm not stressed. I'm not stressed. I'm not stressed. I'm SCREWED IT's SO tough!
Aiyah Relax la..
It's not like it's ThermoDIEnamics..
Yes it is!!
Ahhhhhhhhhhhhhhhhhhhhhhhhh
carnot otto diesel brayton(gas turbine) dual rankine refrigeration cycles... did I miss any?
Refrigeration cycle is a bit weird though it's like playing with mahjong in the wrong direction anti clockwise when all the other cycles flow clockwise and you're not used to the way the cycle flows.
A lot of freaking stuff to remember. like if it's vapour liquid mixture, have to find quality x via x = (v-vf)/(vfg) then find the respective u or h or s otherwise you'll get the wrong ans.
gas relations , only for isentropic processes. (T2/T1)= (P2/P1)^0.4/1.4=(V1/V2)^0.4~ideal gas otherwise PV/T=PV/T eh..
intrapolation sucks
I hope they give nice numbers, so dun have to intrapolate that much
Compressor work will have more so Wactual = Wc/nth<-----Compressor efficiency Pump work will have less so Wactual = (Wp)(nth)<----turbine efficiency dunnoe leh dunnoe wat will come out. Q1 They'll maybe ask us to prove a violation of clausius leads to a violation of the Kelvin- Plank statement. Instead of the other way round, maybe not. Then they'll ask on Clausius inequality.. Part 2 tiny Entropy question. Sin - Sout + Sgen = change in S
Ask you to find Sgen
Adiabetic: entropy by heat = 0
Closed system: entropy by mass=0
steady flow: change in S = 0
Reversible: Sgen =0
For solid/ liquid ==> change in s =mCavlnT2/T1
Q2 Part 1 on Energy balance on steady flow systems. or if they wanna make me work for it.. add Q in..
Ein - Eout = Change in energy --> min(h+ v^2/2) + Qin - mout(h+ v^2/2) = mu(ini) - mu(fin)
But most of the time KE and PE is assumed zero, unless they give u area of inlet or something. then KE is in.
if Steady flow,change in mass flow rate = 0. --> change in energy = 0 Ein=Eout
Mass flow rate = (VA/v) if just mass is (V/v) v is specific volume.
Part 2 Thermal energy reservoirs: 2 thermal reservoirs find --> COP --> heat rejection or something..
Carnot COP HP = 1/(1-Tl/Th) = Qh/Wnet ,Carnot COP R =1/(Tl/Th-1) = Ql/Wnet, efficiency HE = 1/COPhp = Wnet/Qh
Q3Cos last year it's Carnot and otto and last last yr it's gas and refrigeration. so you cancel out from the cycles and you left with Rankine cycle. maybe Reheat. plus work pump and turbine efficiency for kicks... find net work, find efficiency.. blah blah..
Q4 Diesel cycle then they'll throw in one sub question on partial pressure.
not very difficult if u say it like tat but when I see the question I'll totally forget how to do.. I hope i remember.............
I'm not stressed. I'm not stressed. I'm not stressed. I'm SCREWED IT's SO tough!
Aiyah Relax la..
It's not like it's ThermoDIEnamics..
Yes it is!!
Ahhhhhhhhhhhhhhhhhhhhhhhhh
kakashi + 1:41 AM
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