Lecture Objectives: Answer question related to Project 1 assignment Discus the Final Project Learn about Electric Energy Generation

Project 1 New example matlab code on the course website

Final Project Expand this Project Variable speed pumps Different type of chillers Different buildings …. Modeling of processes in the psychrometric chart Will discuss with you in one on one meeting Your ideas from your research, work, internship, life,… Meetings: Today from 2 to 3 pm Tuesday all morning and from 2 pm to 3 pm

Power generation

Power generation in steam turbines (Rankine cycle) Pump Nuclear Coal

Steam powered turbine

Ideal Rankine Cycle 1-2 isentropic pump 2-3 constant pressure heat addition 3-4 isentropic turbine 4-1 constant pressure heat rejection

Ideal Rankine Cycle h1=hf saturated liquid Wpump (ideal)=h2-h1=vf(Phigh-Plow) vf=specific volume of saturated liquid at low pressure qin=h3-h2 heat added in boiler Usually either qin will be specified or else the high temperature and pressure (so you can find h3) qout=h4-h1 heat removed from condenser) wturbine=h3-h4 turbine work

Deviations from Ideal in Real Cycles Pump is not ideal Turbine is not ideal There is a pressure drop across the boiler and condenser We need to sub-cool the liquid in the condenser to prevent cavitation in the pump.

For increasing system efficiency of Rankine Cycle Lower condenser pressure We should have at least 10°C DT between condenser and cooling water or air temperature for effective heat transfer The quality at exit to prevent turbine problems shouldn’t go less than about 88% Superheat the steam more Tmax ~ 620° due to material stress Increase boiler pressure (with same Tmax) Pmax ~ 30 MPa This affects the quality at exit!

Reheat Cycle It allows increase boiler pressure without problems of low quality at turbine exit

Regeneration Preheats steam entering boiler using a feed-water heater, improving efficiency

Further improvements

Analogy with cooling cycles

Gas powered turbine http://www.youtube.com/watch?feature=player_embedded&v=rxps0sZ8T3Y

Combustion product gas powered turbines Limited to gas or oil as a major source of fuel Approximately 55 to 65% of the power produced by the turbine is used for compressor. Gas temperatures at the turbine inlet can be 1200ºC to 1400ºC Because of the power required to drive the compressor, energy conversion efficiency for a simple cycle gas turbine plant is ~ 30%

Combined Cycle (gas and steam) http://www.youtube.com/watch?feature=player_embedded&v=D406Liwm1Jc

Combined heat and power (cogeneration CHP or three generation CCHP) Here, we use thermal energy for heating and/or cooling

Other method for CHP Here, we use mechanical energy for powering vapor compression cooling systems