Warnakulasuriya Primal Deepthi Fernando 1

Warnakulasuriya Primal Deepthi Fernando 


1. PERSONAL DETAILS 

Name: 

Warnakulasuriya Fernando, Primal Deepthi 

Date of Birth: 17 July 1969 

Nationality: 

Contact Details: 

Current 

Employment: 

Previous 

Employment: 

Education 

Qualifications: 

Sri Lankan 

Department of Energy Technology, Division of Applied Thermodynamics 

and Refrigeration, Royal Institute of Technology, 

SE-100 44, Stockholm, Sweden 

Telephone: Office - 0046 (0) 8 7908941, Home - 0046 (0) 73 7763035 

Fax: Office - 0046 (0) 8 203007, 0046 (0) 8 204161 

E-Mail: primal@energy.kth.se 

http://www.energy.kth.se 

Ph.D. student (since 2000) and Teaching Assistant, 

Royal Institute of Technology (KTH), Sweden 

1996 - 1998 Mechanical Engineer (Junior Manager), 

Wall’s Ceylon Ltd (Unilever Group), Sri Lanka. 

1996 Teaching Assistant, University of Moratuwa, Sri Lanka. 

1995 Intern, Sri Lanka Ports Authority, Sri Lanka. 

1994 Intern, Sri Lanka Railways, Sri Lanka. 

1990 Secondary School Teacher, Sri Lanka. 

1999 M.Sc. in Sustainable Energy Engineering, 

Royal Institute of Technology, Sweden. 

Dissertation title: “The behaviour of two-phase flows consisting of various 

air water mixtures through a full scaled mock up of a fuel bundle” 

1996 B.Sc. in Mechanical engineering, 

University of Moratuwa, Sri Lanka. 

Passed with Second Class Honours (Lower division). 

Project entitled “Feasibility Study of Wind Energy in Sri Lanka”. 

Membership of 

Professional 

Societies: 

The Swedish Society of Refrigeration (Svenska Kyltekniska Förenningen). 

ASHRAE (American Society of Heating, Refrigerating and Air-Conditioning 

Engineers. 

Computer Skills: Windows 9x and XP Professional, Microsoft office package, Visio 6.0, 

MathLab, EES, CFD packages and many other application packages. 

Awards and 

Scholarships: 

2000 - 2001, Graduate Study Scholarship from the Department of Energy 

technology, Royal Institute of Technology, Sweden. 

1998 - 1999, International Master Scholarship from Swedish International 

Development Authority (SIDA). 

1992 - 1996, Undergraduate Scholarship from Government of Sri Lanka. 

1980 – 1985, Junior High School Scholarship from Government of Sri Lanka. 

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Sports and Awards: 

Leisure Interests: 

2004 - 2005 Member of Spånga Cricket Club, Sweden. 

2004 - 2005, Member of Energy Football team, Department Energy 

Technology, Sweden 

1993 - 1996, Member of University of Moratuwa Football team, Inter University 

Champion, University Colors, Vice-Captain of the team. 

1993 - 1996, Member of University of Moratuwa Elle team, Inter University runnerup, 

University Colors. 

1985, Member of School Volley Ball Team, School Colors, Under 17 Age Category, 

National Champion. 

1985, Member of School Cricket Team. 

1980 - 1990, Member of Village Softball Cricket Club, District Champion. 

Singing, Traveling, Playing or watching any Kind of Sport, Talking with 

People and Spend time with Family and Friends 

2. RESEARCH 

I am a dedicated research scientist with a strong background in Mechanical Engineering. My 

expertise in this area is the product of experience gained in a variety of industrial and academic 

settings. My long-term goals are to develop new correlations for heat transfer in microchannel heat 

exchangers and modelling the heat transfer and flow behaviours in microchannel heat exchangers. 

My research interests are, 

• The study of behaviours in surface tension forces and capillary actions in microchannels 

• The study of boiling and condensation heat transfer of various fluids in micro channels 

• The study of single and multiphase flows in microchannels 

• The study of applications in heat pump technology for various countries 

I have treated above problems theoretically and experimentally. 

Research Experience 

Charge minimisation of a small capacity heat pump 

The environmental impacts, such as ozone depleting potential (ODP) and greenhouse warming 

potentials (GWP) of some commonly use refrigerants have initiated the search for new kinds of 

refrigerants that are environmentally friendly. Propane is an environmentally friendly refrigerant 

and one of the best candidates to replace conventional refrigerants in existing refrigeration systems 

without significant technical changes in the systems. Propane does not react with engineering 

materials such as aluminium, brass, bronze, copper, stainless steel, silver etc. Therefore it is fully 

compatible with existing components such as heat exchangers, expansion valves, compressors, 

lubricants and copper tubing that are currently used in refrigeration systems. It is a refrigerant that 

has been proposed to replace refrigerant R22 which is widely used in refrigeration and airconditioning 

applications as both have close type of vapour pressure curves. 

However, flammability of propane is a major risk associated with using it as a refrigerant. The fire 

danger can be reduced by minimisation of the refrigerant quantity in a system. If the refrigerant 

quantity of a system could be kept under 150 grams, according to safety regulations, the systems that 

are installed and used even inside private homes will not require special safety devices assuming that 

the system is “hermetic”. Moreover, the lower molecular weight of propane compared to R22 would 

reduce the mass used per system. 

The ongoing project aims to develop a heat pump that uses 150g or less propane having the heating 

capacity of 5kW or more based on the existing knowledge of propane based heat pumps. The longterm 

aim is to reach the best possible heating factor. The extent of heating capacity was chosen by 

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taking into consideration of the Swedish and eventually cumulative European markets for singlefamily 

house heat pumps. 

Developments 

First stage of the project, a heat pump was made using two commercially available brazed plate heat 

exchangers. Variations of the heating capacity and coefficient of performance (COP) for various 

refrigerant (propane) charges were investigated. For all the investigated cases the operational 

conditions were kept constant (evaporation approximately at -8°C and condensing at +40°C). The 

amounts of propane in various parts of the heat pump (evaporator, condenser, liquid line and gas 

line including compressor) were measured while it was in operation. The optimum quantity of 

propane required to obtain best heating factor (COP) was found to be 300g. Around 70 - 80 g of 

propane was found in the evaporator, around 100 - 130 g of propane was found in the condenser and 

around 70 - 80 g of propane was found in the compressor. 

In the second stage of the project, the brazed plate heat exchangers were replaced by commercially 

available minichannel heat exchangers. Experiments showed that a reduction of the optimum 

refrigerant charge by 75 g. However, the performance of the heat pump was lower than that of the 

first stage. 

Based on the understanding gained from the first two stages of the project, I designed three multiport 

minichannel aluminium heat exchangers. The heat exchangers were manufactured in a Swedish 

factory under my supervision. Two of the designed heat exchangers then coupled to the heat pump 

as the condenser and the evaporator, replacing previous heat exchangers by them. Experiments 

showed that the novel design reduced the optimum refrigerant charge by 100 g. The overall heat 

transfer coefficients were increased by more than 50% compared to the brazed plate heat exchangers 

used in the first stage of the project. In addition, the heating factor (COP) of the novel heat pump was 

slightly improved compared to the heat pump tested in the first stage of the project. 

The heat transfer coefficients of the minichannel heat exchanger as the evaporator and the condenser 

were investigated. The novel heat exchanger was tested for single-phase water-to-water heat transfer. 

All experimentally evaluated heat transfer coefficients were compared with existing correlations 

available in literature. New correlations as well as existing correlations from the literature that is 

suited to explain the heat transfer rates were suggested. 

3. TEACHING 

Teaching and Demonstration 

1. Measuring Performance of a Compressor Refrigeration Rig (Demonstrator) (2000-2004) 

This is taught to International and Swedish master students in the M.Sc. course on Sustainable 

Energy Engineering. The duration of the session is 4 hours. Measurements were made at different 

evaporation temperatures on a running compressor. Refrigerating capacities, coefficients of 

performances and various efficiencies of the compressor were calculated and discussed. 

2. Determining Heat Transfer Coefficients for a Finned-Tube Heat Exchanger with Forced 

Convection (Demonstrator) (2000-2004) 

This is demonstrated to International and Swedish students in the M.Sc. course on Sustainable 

Energy Engineering. The object of this Lab session is to determine the overall heat transfer coefficient 

and the heat transfer coefficient related to the fin surface of a heat exchanger placed in an air duct 

with forced convection and cooled on the inside by boiling refrigerant. 

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3. Investigation of heat exchangers (Demonstrator) (2000-2004) 

This is a lab class for 3 rd year undergraduate students. The purpose of this experiment is to compare 

the performance of two different types of heat exchangers. The heat transfer coefficients were 

investigated using Wilson-plot method. 

4. Natural Convection at Vertical Plates (Demonstrator) (2000-2004) 

3 rd year undergraduate students are taught how to determine the heat transfer coefficients on smooth 

vertical plates due to natural convection. 

5. Refrigeration capacity control of a compressor (Demonstrator) (2006) 

This is taught to International and Swedish master students in the M.Sc. course on Sustainable 

Energy Engineering. The duration of the session is 4 hours. This laboratory lesson involves 

measuring the refrigeration capacity and the electric power required for a refrigerating compressor 

that has its capacity control in different ways. 

6. Workshop Technology-Foundry (Demonstrator) (1996) 

While employed as a teaching assistant at the University of Moratuwa (Sri Lanka) I taught this to 1 st 

year undergraduate students. 

Current Teachings 

Energy and Environment - Clean transportations 

This lecture is given to M.Sc. students in Sustainable Energy Engineering. This discusses the 

sustainable transportations, visions of future transportation systems, emissions from fossil fuels and 

alternative fuels for fossil fuels. Total duration of the lecture is 4 hours. 

Teaching Preparations 

1. Sustainable energy engineering - Basic refrigeration and heat pumps 

This lecture is in preparation for M.Sc. students in the Program of Sustainable Energy Engineering. 

The lecture covers refrigeration systems, refrigeration equipments, refrigerants and properties, 

refrigerant mixtures, secondary refrigerants in indirect systems, vapour compression cycle, 

alternative cycles etc. 

2. Evaporators and condensers 

This is a special topic in refrigeration technology taught to M.Sc. students in the Program of 

Sustainable Energy Engineering and B.Sc. undergraduate students. 

3. Introductions to thermodynamics 

This is a lecture for undergraduate students detailing the basics of thermodynamics. The course 

textbook is “Introduction to thermodynamics: classical and statistical” by Sonntag and Van Wylen. 

4. PUBLICATIONS 

4.1. Refereed journal articles 

1. Primal Fernando, Björn Palm, Per Lundqvist and Eric Granryd, “Propane heat pump with low 

refrigerant charge: design and laboratory tests”, International Journal of Refrigeration Volume 27, 

Issue 7, November 2004, Pages 761-773, 

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2. Primal Fernando and Per Lundqvist, “Refrigeration systems with minimized refrigerant charge - 

System design and performance”, Proc. IMechE Vol. 219 Part E: Process Mechanical Engineering, 15 

June 2005. 

3. Primal Fernando, Björn Palm, Per Lundqvist, Eric Granryd, Performance of a Single - family Heat 

Pump at Different Working Conditions Using Small quantity of Propane as Refrigerant, Journal of 

Experimental heat transfer (Accepted, Feb. 2006). 

4.2. Papers under internal review process 

1. Primal Fernando, Björn Palm, Per Lundqvist, Eric Granryd , A Multiport Minichannel Aluminium 

Heat Exchanger, Part I: Investigation of Single-Phase Heat Transfer Coefficients in a in Both Tube 

Side and Shell Side by Wilson Plot Method, Journal of Experimental heat transfer. 

2. Primal Fernando, Björn Palm, Per Lundqvist, Eric Granryd, A Multiport Minichannel Aluminium 

Tube Heat Exchanger, Part II: Working as an evaporator with refrigerant propane – Experimental 

Study of Heat Transfer and Comparison with Available Correlations in the Literature. 

3. Primal Fernando, Björn Palm, Per Lundqvist, Eric Granryd, A Multiport Minichannel Aluminium 

Tube Heat Exchanger, Part III: Working as an condenser with refrigerant propane – Experimental 

Study of Heat Transfer and Comparison with Available Correlations in the Literature. 

4.3. Paper presentations in conferences 

1. W. Primal D. Fernando, Oxana Samoteeva, Per Lundqvist and Björn Palm, “Charge Distribution in 

a 5kW Heat Pump Using Propane as Working Fluid. Part 1: Experimental Investigation”, 

Proceedings: 16. Nordiske Kolemode og 9. Nordiske Varmepumpedage, Copenhagen, Denmark, 

August 29-31, 2001 (page299). 

2. W. Primal D. Fernando, Björn Palm, Eric Granryd, Oxana Samoteeva and Klas Anderson, “The 

Behaviour of Small Capacity (5kW) Heat pump with Micro-Channelled Flat Tube Heat Exchangers – 

Proceedings: Zero Leakage and Minimum Charge”, Efficient Systems for Refrigeration Air 

Conditioning and Heat pumps, Stockholm, Sweden August 26-28, 2002 (page 179). 

3 W. Primal D. Fernando, Björn Palm, Eric Granryd and Klas Andersson, “Mini-Channel Aluminium 

Heat Exchangers with Small Inside Volumes” – Proceedings: 21 st IIR International Congress of 

Refrigeration, Washington D.C., USA, August 17-22, 2003. 

4. W. Primal D. Fernando, Houde Han, Björn Palm, Eric Granryd and Per Lundqvist, “The Solubility 

of Propane (R290) with Commonly Used Compressor Lubrication Oils. International conference on 

compressors and their systems”, IMECHE Conference Transactions 2003-4, Professional Engineering 

Publishing, ISSN 1356-1448. 

5. O. Samoteewa, P. Fernando, B. Palm, P. Lundquist, “Charge Distribution in a 5kW Heat Pump 

Using Propane as Working Fluid. Part 1I: Modelling of Liquid hold-up” Proceedings: 16. Nordiske 

Kolemode og 9. Nordiske Varmepumpedage, Copenhagen, Denmark, August 29-31, 2001. 

6. O. Samoteewa, E. Granryd, B. Palm and P. Fernando, “Modelling of the amount of refrigerant and 

pressure drop in a rectangular copper microchannel evaporator – Proceedings: Zero Leakage and 

Minimum Charge”, Efficient Systems for Refrigeration Air Conditioning and Heat pumps, 

Stockholm, Sweden August 26-28, 2002 (page 449). 

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7. B. Palm, P. Fernando, K. Andersson, P. Lundqvist and O. Samoteeva, “Design a heat pump for 

minimum charge of refrigerant” , 8 th International Energy Agency, Heat Pump conference 2005, 

Global Advances in Heat Pump Technology, Applications and Markets, Las Vegas, Nevada, USA, 

May 30 – June 2, 2005. 

7. REFEREES 

Professor emeritus Eric Granryd 

Department of Energy Technology 

Division of Applied Thermodynamics and Refrigeration 

Royal Institute of Technology (KTH) 

SE-100 44 Stockholm, Sweden 

Phone: +46 (0) 70 7640310; Fax: +46 (0) 8 20 30 07 

granryd@energy.kth.se 

Assoc.Prof./Head of Division Björn Palm 





Phone: +46 (0) 8 7907453; Fax: +46 (0) 8 20 30 07 

bpalm@energy.kth.se 

Assoc.Prof./Head of Division Per Lundqvist 





Phone: +46 (0) 8 790 7452; Fax: +46 (0) 8 20 30 07 

perlundq@energy.kth.se 

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Warnakulasuriya Primal Deepthi Fernando 1

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