LOVELY PROFESSIONAL UNIVERSITY

PHAGWARA (PUNJAB)

TERM PAPER

SUB: - MEC-203 (ENGINEERING THERMODYNAICS)

COURSE: - B-TECH MECHANICAL ENGG. (LEET-09)

TOPIC:-PRACTICAL APPLICATION OF RANKINE CYCLE

SUBMITTED TO; SUBMITTED BY;

Mr. SREEDHAR SIR, OMKAR KUMAR JHA

(MECHANICAL ENGG.) RH-4901-A12

10902923

INTRODUCTION

The Rankine cycle, like the Stirling cycle is an external combustion cycle. That is the

combustion process is external to cylinder containing the working gas. The Rankine cycle is

characterized by the working gas undergoing a phase change (from liquid to gas) which can be

utilized to achieve high power densities. The most familiar Rankine engine is the steam engine

in which water is boiled by an external heat source, expands and exerts pressure on a piston or

turbine rotor and hence does useful work. A number of the products below make use of this

concept. However, one of them (the Energetix Genlec formerly known as Baxi Inergen) is an

organic Rankine engine which uses an organic fluid (a refrigerant) and operates at temperatures

and pressures much closer to conventional heating and refrigeration appliances. This has the

significant advantage of allowing the use of conventional, mass produced components and

eliminates many of the technical challenges of steam engines.

Dig.:- PRACTICAL APPLICATION

WHERE: - (may not shown in fig... but abbreviated later)

Q = Heat flow rate to/from the system

M Mass flow rate

W Mechanical power used or provided to the system

thermal = Efficiency (thermodynamic)

turbinepump , = Efficiency of feed pump (in compression) and Efficiency of

turbine (In expansion)

.....,,, 4321 hhhh = Specific enthalpy at different points

21, PP = Pressure after and before the compression process.

PROCESS STEPS

There are four processes in the Rankine cycle; these states are identified by number in the

diagram to the right.

Process 1-2: The working fluid is pumped from low to high pressure, as the fluid is a

liquid at this stage the pump requires little input energy.

Process 2-3: The high pressure liquid enters a boiler where it is heated at constant

pressure by an external heat source to become a dry saturated vapor. The input energy

required can be easily calculated using mollier diagram or h-s chart or enthalpy-entropy

chart

Process 3-4: The dry saturated vapor expands through a turbine, generating power. This

decreases the temperature and pressure of the vapor, and some condensation may occur.

The output in this process can be easily calculated using the Enthalpy-entropy chart

Process 4-1: The wet vapor then enters a condenser where it is condensed at a constant

pressure to become a saturated liquid.

In an ideal Rankine cycle the pump and turbine would be isentropic, i.e., the pump and turbine

would generate no entropy and hence maximize the net work output. Processes 1-2 and 3-4

would be represented by vertical lines on the T-S diagram and more closely resemble that of the

Carnot cycle. The Rankine cycle shown here prevents the vapor ending up in the superheat

region after the expansion in the turbine, which reduces the energy removed by the condensers.

EQUATIONS

23 hhM

Qin pumppump

pump PPPhh

M

W

)( 121112

14 hhM

Qout turbinesturbine hhhhM

W )( 4343

in

turbine

in

pumpturbine

thermalQ

W

Q

WW

These are the equations which are used during different

process and calculations of the cycle and entities…

APPLICATIONS

In general science and day to day uses the efficient cycles and process

are being adapted due to their general and easy uses and high efficiency …

There are some applications in use of Rankin: -

A hybrid power generation system: solar-driven Rankine

Engine } & Hydrogen storage

GENERAL SYSTEM DESCRIPTION

The schematic of the proposed solar power –Rankin-based hybrid power

generation system is shown in fig...

The system is consisted of 2 main parts

1-solar collector rankine cycle power generation system described by kuo -et-al

(1998)

As shown in figure 2 the solar radiation is trapped by the solar collector and

energy is transferred to the working fluid circulating in the rankine based thermodynamic

cycle. A turbine generates the mechanical power from the expansion of the working fluid.

2- Hydrogen production and storage system. In this system the excess energy

from a wind power system can be stored by using electrolysis process with the electricity

from the wind turbine to produce hydrogen…..

SOLAR-RANKINE POWER GENERATION UNIT

The Ts (temperature vs. entropy) diagram describing the Rankine cycle process is shown in

Figure . With numbers of the stages matching that of Figure 2. Normal incident solar radiation is

Collected by the parabolic trough collectors and concentrated on the collector absorber tubes.

The working fluid, with the set flow rate m is evaporated while passing through the collector

Absorber tube (stages 1 and 2). An optional auxiliary heater is placed following the collectors

(stages 3 and 4), powered by back up electricity or, in the current hybrid design, by the hydrogen

Burner. This heater, controlled by the collector outlet temperature, serves as the backup power

source during temporary solar down time (such as cloud passing) to prevent the system from

frequent stop, and as the working fluid temperature regulator during inoperative and start-up

times. Mechanical power is produced by passing the working fluid vapor through a steam

turbine (stages 5 and 6), which then drives a generator to produce electricity. The depressurized

vapour is condensed in an air or water-cooled, constant pressure condenser (stages 7 and 8), and

a circulation pump increases working fluid pressure to complete the working cycle (stages 8, 9

and

1). An electricity power control unit directs and allocates the output electricity toward either the

Application usage or the hydrogen production system. The controller also turns on or o! the

pump and the heater according to the situation arising.

For the proposed solar-Rankine hybrid system, the time transient solar radiation controls the

system dynamics. Since the flow rate m is constant during operation, sometimes the excess solar

radiation input would superheat the working Fluid in the collector absorber tubes. And some

other times, the solar radiation input is not sufficient to completely evaporate the working fluid

to

the saturated vapour state at the collector exit (stage 2). To avoid the wet vapour from entering

the turbine, a control unit is recommended to shut off the circulation pump when the solar

radiation is not sufficient to completely evaporate the working fluid. The control unit is often

connected to a temperature sensor in the collector or a pyrheliometer, and programmed to switch

the circulation pump on and o!, depending on the collector temperature readings or the direct

Normal solar radiation reading .

The optional auxiliary heater allows for the greater system flexibility while operating under

Different conditions. The control unit can be extended to integrate the auxiliary heater into the

overall operating schemes. The control unit can be set to turn on the auxiliary heater during

the temporary solar down time (such as cloud passing) to sustain continuous operations. Also,

the

heater can be used to regulate the temperature of the working fluid, and the turbine entrance

conditions.

For the domestic scale solar Rankine systems, the simple, inexpensive and easy to maintain

control system is strongly recommended over the more complicated systems, which may give

better operating efficiencies, but are harder to install, operate and maintain, and are more

expensive.

The sophisticated control systems are more suitable for larger scale power generation systems.

APPLICATION-2

RACER (Rankine Cycle Energy Recovery)

RACER (Rankine Cycle Energy Recovery) was the Naval Sea Systems Command [NAVSEA]

program to design and develop an advanced, combined gas turbine and steam turbine [COGAS]

power plant. The RACER (Rankine Cycle Energy Recovery) system was planned for

development and application to US combatant and auxiliary ships. The system will use the

exhaust energy from an 18MW gas turbine to produce steam and generate power in excess of

6MW for additional ship propulsion power. The RACER System is expected to provide an

overall propulsion fuel reduction upwards of 25%.

The RACER system provides several advantages to a gas turbine powered ship. one of which is

improved fuel efficiency for significant annual fuel savings. This saving does not come free,

however, since; in general, any additional system installed in the ship will have some

maintenance requirements. In keeping with the US Navy's Current emphasis, a key philosophy in

the design of the RACER system was to minimize this maintenance burden.

Marine and land based power plants can produce exhaust products in a temperature range of 350-

1850.degree. F. In most applications, the exhaust products are released to the environment and

the thermal energy is lost. In some instances, however, the thermal energy is further utilized. For

example, the thermal energy from the exhaust of an industrial gas turbine engine (IGT) has been

used as the energy source to drive a Rankine cycle system.

Rankine cycle based power plants Inside a condensing steam turbine - the steam expands below the atmospheric pressure and then

"condenses" while heating the cooling water in a condenser. After the steam exits the outlet of

the condensing turbine, the steam's pressure is so low, it is no longer available for providing

power for industrial applications.

Condensing steam turbines could be used in industrial power plants as condensing tails

connected to back-pressure turbines. In cases of low demand for process steam the steam surplus

is run through the condensing tail to generate more power.

A condensing steam turbine does not differ much from a back-pressure turbine in respect of its'

overall dimensions, steam values (with the exception of outlet pressure), delivery time and price.

The steam condensing equipment requires some additional "balance of plant" investments plus

the availability of cooling water. A 1 MW condensing steam turbine plant needs about 0.1 m3/s

of cooling water.

Organic rankine cycle

The Organic Rankine cycle (ORC) is named for its use of an organic, high molecular mass fluid

with a liquid-vapor phase change, or boiling point, occurring at a lower temperature than the

water-steam phase change. The fluid allows Rankine cycle heat recovery from lower temperature

sources such as industrial waste heat, geothermal heat, solar ponds etc. The low-temperature heat

is converted into useful work, that can itself be converted into electricity. A prototype was first

developed and exhibited in 1961 by Israeli solar engineers Harry Zvi Tabor and Lucien Bronicki.

The working principle of the organic Rankine cycle is the same as that of the Rankine cycle : the

working fluid is pumped to a boiler where it is evaporated, passes through a turbine and is finally

re-condensed.

In the ideal cycle, the expansion is isentropic and the evaporation and condensation processes are

isobaric.

In the real cycle, the presence of irreversibilities lowers the cycle efficiency. Those

irreversibilities mainly occur :

During the expansion : Only a part of the energy recoverable from the pressure difference

is transformed into useful work. The other part is converted into heat and is lost. The

efficiency of the expander is defined by comparison with an isentropic expansion.

In the heat exchangers : The working fluid takes a long and sinuous path which ensures

good heat exchange but causes pressure drops that lower the amount of power

recoverable from the

cycle.

Improvement of the organic Rankine cycle

In the case of a "dry fluid", the cycle can be improved by the use of a regenerator : Since the

fluid has not reached the two-phase state at the end of the expansion, its temperature at this point

is higher than the condensing temperature. This higher temperature fluid can be used to preheat

the liquid before it enters the evaporator.

A counter-current heat exchanger is thus installed between the expander outlet and the

evaporator inlet. The power required from the heat source is therefore reduced and the efficiency

is increased

Applications for the ORC

The organic Rankine cycle technology has many possible applications. Among them, the most

widespread and promising fields are the following:

Waste heat recovery

Waste heat recovery is the most important development field for the Organic Rankine Cycle

(ORC). It can be applied to heat and power plants (for example a small scale cogeneration plant

on a domestic water heater), or to industrial and farming processes such as organic products

fermentation, hot exhausts from ovens or furnaces, flue gas condensation, exhaust gases from

vehicles, intercooling of a compressor, condenser of a power cycle, etc.

Biomass power plant

Biomass is available all over the world and can be used for the production of electricity on small

to medium size scaled power plants. The problem of high specific investment costs for

machinery such as steam boilers are overcome due to the low working pressures in ORC power

plants. The ORC process also helps to overcome the relatively small amount of input fuel

available in many regions because an efficient ORC power plant is possible for smaller sized

plants.

Geothermal plants

Geothermic heat sources vary in temperature from 50 to 350°C. The ORC is therefore perfectly

adapted for this kind of application. However, it is important to keep in mind that for low-

temperature geothermal sources (typically less than 100°C), the efficiency is very low and

depends strongly on heat sink temperature (defined by the ambient temperature).

Solar thermal power

The organic Rankine cycle can be used in the solar parabolic trough technology in place of the

usual steam Rankine cycle. The ORC allows a lower collector temperature, a better collecting

efficiency (reduced ambient losses) and hence the possibility of reducing the size of the solar

field.

CONCLUSION

So according to above all the examples the rankine have a major drawback that it losses the

steam and the heat energy form the boiler or condenser surface….

But overall ,the efficiency of the rankine is good and many of its application is energy efficient

and the highly cost reductive in nature,,,

REFRENCES

1. http://wapedia.mobi/en/Organic_Rankine_cycle

2. http://www.crazyengineers.com/forum/mechanical-civil-engineering/21507-rankine-

cycle-based-power-plants.html

3. http://nptel.iitm.ac.in/courses/IIT-

MADRAS/Applied_Thermodynamics/Module_5/2_%20Rankinecycle.pdf

4. http://www.taftan.com/thermodynamics/RANKINE.HTM

5. http://www.answers.com/topic/rankine-cycle

6. http://en.wikipedia.org/wiki/Rankine_cycle

7. http://www.rankinecycle.com/

8. BOOKS OF THERMOYNAMICS

JOURNALS

http://saeeng.saejournals.org/content/2/1/67.abstract

http://www.waset.org/journals/ijcee/v2/v2-1-3.pdf