Shaft Power Generation Devices - 2 P M V Subbarao Professor Mechanical Engineering Department A List of Artificial Animals for Human Development !!!!

Control Mass based Power Generation Systems Found to be best choice for vehicular applications. Otto cycle is best suited for light and high speed applications. Diesel cycle is for high torque and low load applications. Not found to be good choice for electricity generation. Reciprocating systems are not reliable for continuous working. Rotating machines (control volumes) are best suitable for continuous working.

Rankine & Brayton Cycles Process 1  2 Isentropic compression Process 2  3 Constant pressure heat addition Process 3  4 Isentropic expansion Process 4  1 Constant Pressure heat rejection p=constant

Schematic of Rankine & Brayton cycles

First Law Analysis of Cycle

Performance Analysis

Variation of Brayton Cycle Complete Expansion in turbine: Partial Expansion in turbine to create High Velocity Jet:

Air Standard Brayton Cycle for Power Plant Design parameter:

Pressure Ratio Vs Efficiency

Pressure Ratio Vs Specific Work output

Fuel Natural gas Frequency 60 Hz Gross Electrical output MW* Gross Electrical efficiency 36.9 % Gross Heat rate 9251 Btu/kWh Turbine speed 3600 rpm Compressor pressure ratio 32:1 Exhaust gas flow 445 kg/s Exhaust gas temperature 612 °C NOx emissions (corr. to 15% O2,dry) < 25 vppm GT24 (ISO 2314 : 1989)

Fuel Natural gas Frequency 60 Hz Gross Electrical output MW* Gross Electrical efficiency 36.9 % Gross Heat rate 9251 Btu/kWh Turbine speed 3600 rpm Compressor pressure ratio 32:1 Exhaust gas flow 445 kg/s Exhaust gas temperature 612 °C NOx emissions (corr. to 15% O2,dry) < 25 vppm 9756 kJ/kWh

Analysis of Siemens Gas Turbine Power Plant The rated net Power output = 152 MW Net (Irreversible) efficiency of 36.1%. The pressure ratio (r p ) is 16:1. The turbine entry temperature is C. Actual(Irreversible) exhaust temperature is 550 C.

Rankine Cycle for Low Cost Power Generation

Simple Rankine cycle

Rankine Cycle for Nuclear Power Plant

Rankine Cycle for Geothermal Power Plant

Ranking Cycle for Solar Thermal Power Plant

Ranking Cycle for Biomass Thermal Power Plant

Selection of Fluids : Thermodynamics The selection of working fluids and operational variables is very important to obtain better system performance. The thermodynamic properties of working fluids will affect the system efficiency, operation, and environmental impact. Fluid must be selected in accordance to the temperature level of the heat source. Minimum temperature difference between the source and working fluid during heat addition (pinch point) is limiting factor for heat transfer

Candidate Working Substances for Rankine Cycle Working Substances must be selected in accordance to the heat source temperature level (T cr < T in-source )

Selection of Fluids : Ecology Environmental impacts and restrictions by using organic substances Inflamable and/or toxic and/or GWP (Global Warming Potential) and/or ODP (Ozone Depletion Potential)

Optimal Design of Vapour Power Plant

p max =10MPa

The Regenerative Cycle T s 3 4

Regeneration Through Closed Feed Water Heater (Throttled Condensate)

Thermodynamic Analysis of A Power Plant

More Cycles for Exotic Needs of Urban World …….

An Urban world that was present till the end of first decade of the 20th century. Only fresh foods that could be grown locally were available, and they had to be purchased and used on a daily basis. Meat was bought during the daily trip to the butcher's; the milkman made his rounds every morning. If you could afford weekly deliveries of ice blocks—harvested in the winter from frozen northern lakes—you could keep some perishable foods around for 2 or 3 days in an icebox. New York was a virtual ghost town in the summer months. Homes were built with natural cooling in mind. Ceilings were high, porches were deep and shaded, and windows were placed to take every possible advantage of cross-ventilation

The Necessity (mother) Delivered a Dangerous Baby Three American corporations launched collaborative research to develop a less dangerous method of refrigeration; their efforts lead to the discovery of Freon. In just a few years, compressor refrigerators using Freon would became the standard for almost all home kitchens. Only decades later, would people realize that these chlorofluorocarbons endangered the ozone layer of the entire planet

Urban Life after the end of first decade of the 21 st century. Fresh foods of all kinds were available just about anywhere in the country all year round. The milkman was all but gone and forgotten, and the butcher now did his work behind a counter at the supermarket. Indeed, many families concentrated the entire week's food shopping into one trip to the market, stocking the refrigerator with perishables that would last a week or more. New York is a busy town in the summer months. Buildings are totally isolated from fresh air.

Creation of Artificial Temperature/Quality

Performance Index The performance of refrigerators and heat pumps is expressed in terms of coefficient of performance (COP), defined as Under the same operating conditions, the COPs are related by

Why not use the reversed Rankine cycle for Refrigeration ? Very costly to expand the liquid using a turbine with very low or negligible power output!?! May become negative under irreversible conditions. Cheaper to have irreversible expansion through an expansion valve.

Thermodynamics of Ideal VCR Cycle Ideal Vapor-Compression Refrigeration Cycle Process Description 1-2 Isentropic compression 2-3 Constant pressure heat rejection in the condenser 3-4 Throttling in an expansion valve 4-1 Constant pressure heat addition in the evaporator

The P-h diagram is another convenient diagram often used to illustrate the refrigeration cycle.

Samsung Split A/c Model No : AQ24UUA Cooling Capacity : 7.03kW Power Consumption (Cooling) : 2,600Watts Refrigerant Type R22 The refrigerant leaves the evaporator at 7.2 o C Condenser pressure : 2.71 MPa.

Heat Pump Systems

The gas power cycle can be used as refrigeration cycles by simply reversing them. Of these, the reversed Brayton cycle, which is also known as the gas refrigeration cycle, is used to cool aircraft. Further Modification this cycle is used to obtain very low (cryogenic) temperatures. The work output of the turbine can be used to reduce the work input requirements to the compressor. Thus, the COP of a gas refrigeration cycle is Gas Refrigeration Systems

Air Standard Refrigeration Cycle for Aircraft Cooling 1

Air Craft Engine Bleed for Refrigeration System

Air Craft Engine Refrigeration System Air to Cabin

Absorption Refrigeration Systems

Compression to Absorption Refrigeration Systems

Thermoelectric Refrigeration Systems A refrigeration effect can also be achieved without using any moving parts by simply passing current through a closed circuit made up of two dissimilar materials. This effect is called the Peltier effect, and a refrigerator that works on this principle is called a thermoelectric refrigerator.