Fossil fuel consumption in the recent years has been increasing and the burning of fossil fuel is said to be a major contributor towards global warming, acid rains, air, water and soil pollution, forest devastation and radioactive substances emissions. Besides the environment, the fossil fuel prices fluctuate considerably, usually going up and being very expensive in many countries. Most importantly, the quantity of fossil fuels, like petroleum,natural gas, and coal can only decrease since they are non-renewable resources. As a result many countries have been investing billions of dollars in new technologies and demand for sophisticated power supply options is greatly increased. In a typical developed country as much as 40% of total fuel consumption is used for industrial and domestic space heating and process heating. Of this around one third is wasted. Currently recovering low temperature heat which includes Industrial waste heat, geothermal energy, solar heat, biomass and so on could be a very critical and sustainable way to solve energy crisis. Utilising waste heats along with attempts for the use of renewable sources as low grade thermal heat has motivated us to develop a project based on ORC.

1. DON BOSCO INSTITUTE OF TECHNOLOGY
Department Of Mechanical Engineering
Power Generation Using Low Grade Energy Source From ORC
Under the guidance of
Dr. N. M. Rao
GROUP MEMBERS
Pankaj Nemade (BE Mech A 47)
Ammar Qazi (BE Mech A 53)
Aditya Rokade (BE Mech A 62)
Runal Naik (BE Mech A 78)

2. PROBLEM STATEMENT
• Fossil fuel consumption in the recent years has been increasing and the burning of fossil fuel
is said to be a major contributor towards global warming, acid rains, air, water and soil
pollution, forest devastation and radioactive substances emissions. Besides the
environment, the fossil fuel prices fluctuate considerably, usually going up and being very
expensive in many countries.
• Most importantly, the quantity of fossil fuels, like petroleum,natural gas, and coal can only
decrease since they are non-renewable resources.
• As a result many countries have been investing billions of dollars in new technologies and
demand for sophisticated power supply options is greatly increased.
• In a typical developed country as much as 40% of total fuel consumption is used for
industrial and domestic space heating and process heating. Of this around one third is
wasted.
• Currently recovering low temperature heat which includes Industrial waste heat, geothermal
energy, solar heat, biomass and so on could be a very critical and sustainable way to solve
energy crisis. Utilising waste heats along with attempts for the use of renewable sources as
low grade thermal heat has motivated us to develop a project based on ORC.

3. METHODOLOGY
• The working principle of an ORC is similar to a normal Rankine Cycle.
• The main difference is the use of organic substances instead of water or steam as
working fluid.
• The organic working fluid has high molecular mass and boiling point occurring at
low temperature than the water-steam phase change in Rankine cycle.
• It is thus able to use low temperature heat sources such as biomass combustion ,
industrial wastes heat, geothermal heat ,and solar power plants to produce
electricity.
• The fluid is chosen to best fit the heat source according to their differing
thermodynamic properties thus obtaining higher efficiencies.

4. BLOCK DIAGRAM OF ORC

5. WORKING OF ORC

6. NATURAL CIRCULATION LOOP FOR SINGLE PHASE FLUID

7. STEADY STATE TEMPERATURE DISTRIBUTION AND FLUID FLOW
ACROSS LOOPS

8. ADVANTAGES OF NATURAL CIRCULATION LOOP
• The reliability of the instrument increases since there is no moving part.
• The life of model increases.
• No running and maintenance cost.
• Can be operated theoretically for infinite time.
• Since there is no pump or other moving part so there is no lubrication
required.This prevents the organic fluid from getting contaminated.
• No recycling of fluid is required since there is no contamination.

9. CHALLENGES TO DEVELOP MULTIPHASE NCL LOOP
• There are chances of reverse flow into the NCL loop which needs to be taken care of.
• Leak proof ORC system to be developed since ORC fluids are costlier than steam.
• Since there is no turbulent or laminar flow for two phase fluid, the fluid flow in
Multiphase NCL Loop has to be analysed for different flow regimes:
1. Bubbly flow: It is the formation of bubbles in the pipe which can lead to cavitation.
2. Plug flow: These bubbles join to form larger gas plugs.The plugs flow in the upper part
due to gravity effect.
3. Stratified Flow: The phases are completely separated with gas on the upper part and
liquid in the lower part.
4. Wavy flow : This takes place at higher velocities in which waves are formed on the
phase boundaries resulting in more friction between phases.
5. Slug flow : Waves in the flow reach the top of the pipe , closing the gas path in the
top.This results in suden pressure changes leading to shocks and vibrations.

10. 6. Annular flow: In this the liquid forms a coat all around the pipe walls.
• These flows have to be analysed using Programming and Simulation software.
• Physical model of NCL loop to be developed for experimentation.

11. OBJECTIVES
• To develop a numerical computational model of ORC using programming
language such as FORTRAN.
• To analyse the different fluid regimes in multiphase natural circulation loop.
• To design and fabricate the natural circulation loop model and analyse the flow
conditions at various points.
• To study the effect of different organic fluids on the performance of Organic
Rankine Cycle.

12. COMPARISON OF ORC WITH OTHER CYCLES
• There are some alternatives for power generation for low temperature heat sources
which include Kalina cycle, and Transcritical carbon dioxide cycle .
• These technologies have been deployed successfully for power generation in many
diverse applications from domestic to industrial and also for the purpose of combined
heat and power.
• The ORC, in particular, is an attractive proposition due to its similarity with the well-
established steam Rankine-cycle engine, relatively high efficiency compared to the
aforementioned low-temperature heat conversion alternatives, and the
accompanying wealth of operational and maintenance experience.
• ORC systems have the design option of employing a number of organic working fluids,
ranging from refrigerants to hydrocarbons and siloxanes ,including working fluid
mixtures in order to optimize the heat transfer (and heat recovery) from/to the waste
heat source and heat sink.

13. DIFFERENCE BETWEEN RANKINE AND ORC
Criteria Rankine Cycle Organic Rankine Cycle
Thermodynamic features High specific enthalpy drop Small specific enthalpy drop
Superheating needed to avoid
droplet erosion
No superheating needed
Operation and maintenance Water treatment required Non-oxidizing working fluids
Certified personnel Non-specialized personnel
High pressures and
temperatures
Fully automatic
Low condensation pressures Near-atmospheric
condensation
Miscellaneous Typical for plants >10 MWe and
heat input temperatures >450
◦C
Available for low capacity and
low heat-source temperature
Low off-design flexibility High off-design flexibility
Low performance at part-load Good performance at part-load

14. ADVANTAGES OF ORC OVER TRADITIONAL RANKINE CYCLE
• Suitable for lower temperature applications.
• Low rotation and tip speed
• Lower maintenance cost than with steam turbine
• Design flexibility with the option to utilize the most efficient working fluid.
• Higher Molecular weight than water will increase mass flow rate for same sizes of
turbine.
• Larger mass flow rate gives better turbine efficiencies with less turbine losses.
• Simple and reliable maintenance makes for long product life.
• High market availability of chemicals/fluids with refilling rarely required.

15. SELECTION OF ORGANIC FLUIDS
Selection of the working fluid for use in ORC cycles is a crucial point, because depending on
the application, the source and the heat level to use, the fluid must have optimal
thermodynamic properties at lowest temperatures and pressures and also satisfy several
criteria as follow:
• Environmental concern
Some fluids are restricted by International Agreements depending on their Ozone
Depletion Potential (ODP) defined and limited by Montreal Protocol or Global Warming
Potential (GWP) by Kyoto Protocol, which, intend to prevent the destruction of the ozone
layer and emission of gases that cause the greenhouse effect.
• Security
The fluid must be non-toxic (because of the problems that can occur in the case of leaks
in the atmosphere or in handling), non-corrosive (it obviously avoids major maintenance
costs and/or installation damage) and non-flammable. For this, the standard security
classification 34 of ASHRAE is often used as an indicator of the danger level of fluids.

16. • Stability
The chemical stability of the used fluid limits the heat source temperature. When fluids
are exposed to certain temperatures, they could decompose, producing substances which
could cause a different cycle operation to that initially designed. Moreover, toxic and
irritating compounds could induce health problems in case leaks occur.
• Pressure
A fluid requiring high pressure to achieve an efficient process increases the cost of
equipment due to the greater resistance required, increasing also the complexity of the
plant.
• Availability and low cost
A fluid of low availability and/or high cost limits its use in ORC plants for obvious reasons
in the financial viability of the projects.
• Latent heat and molecular weight
With higher molecular weight and the latent heat of the fluid, more energy from the
heat source in the evaporator will be absorbed and, thus, reducing the size of the
installation and use of the pump due to lower mass flow required.

17. Low freezing point
The freezing point of the fluid must be lower than the lowest temperature of the cycle.
Curve of saturation
The thermodynamic properties of the fluid imply that the slope of the saturation curve
thereof is negative, vertical or positive, which markedly affecting the design and efficiency of
the ORC.The ideal working fluid will be that whose saturated vapor line is parallel to the
expansion of the turbine, ensuring maximum efficiency

18. TEMPERATURE-ENTROPY DIAGRAM FOR DRY, WET AND
ISENTROPIC ORC FLUID

22. SCOPE OF ORC
• Rural distributed electricity generation and better waste heat recovery of different industries
in addition to renewable based power generation can benefit from ORC as it is a very
environmentally friendly option to meet an important need.
• The project can also help rural areas especially in developing countries like India,with a
system that can be applied and manufactured locally and can replace or supplement fossil
fuels in off grid areas by generating clean power at low level cost.
• Installation of ORC by current strength,India has saved 8 Crore rupees every year since 1994.
Cement industry
• Production: 10000 metric tonnes per day
• Energy consumption:5GJ per ton
• Energy produced by ORC:1MW per kiloton
• If used it can meet 20% demand of cement industry already working
Solar Generators
• Generally Steam Rankine Cycle are used here ,but if lower temperature is needed ,mostly
ORC is good.

23. Biomass
• 32% of energy produced.
• 70% of dependant population
• If ORC is installed with an efficiency of 10%,then 18000 MW of electricity generation
takes place.

24. India needs move towards renewable sources such as ORC because India is signatory to :
(1)Sustainable developemental goals by 2030
(2)Renewable energy by 2040.
(3)Kyoto protocal 1992 which mainly focuses on climate related issue
(4)Paris climate change.

25. REFERENCES
• N.M. Rao, M. Mishra, B. Maiti, P.K. Das, Effect of end heat exchanger parameters on the
performance of a natural circulation loop, Int. Comm. Heat Mass Transfer 29 (2002) 509–518.
• N.M. Rao, Investigations on buoyancy induced circulation loops, Ph.D., Thesis, Indian Institute
of Technology, Kharagpur, 2002.
• Fluid selection for a low-temperature solar organic Rankine cycle. Bertrand Fankam Tchanche
*, George Papadakis, Gregory Lambrinos, Antonios Frangoudakis. Department of Natural
Resources and Agricultural Engineering, Agricultural University of Athens, 75 Iera Odos Street,
11855 Athens, Greece.
• Analysis of Low Temperature Organic Rankine Cycles for Solar Applications" (2013).Theses and
Dissertations.Paper 1113. Li, Yunfei. Lehigh University.
• N.M. Rao, M. Mishra, B. Maiti, P.K. Das, Stability Behavior of a Natural Circulation Loop With
End Heat Exchangers.