1. Refrigerants & Coolants
Bartosz Zajaczkowski, PhD
Lecture 1

2. Introduction

3. Today topics
What is this class all about?
Readings, homeworks & examination
Contact information
Introduction to refrigerants and coolants
Types of refrigerants
Historical development of refrigerants

4. What I will learn in this class?
What types of substances are used in refrigeration systems?
What are the most important properties of refrigerants?
How to choose proper refrigerant for the job?
What are the technical, ecological and safety requirements for refrigerants?

5. Problem questions
Problems and questions are indicated with letter Q and this color (cayenne).

6. Homework readings
Additional material to be studied at home is indicated with letter R and this color (ocean).
Estimated reading time is usually provided. However, in-depth study might require more time.

7. Examination
Final test will take place during the last lecture. This is going to be a multiple choice test, that will cover all the topics presented in the class, as well as assigned reading materials.
Test will be written in-class and will take 45 minutes. Participants will be notified about the results via Edukacja.CL within a few days. Students who must be absent for some reason, must arrange to be excused in advance.

8. Make-up test
For those who miss or fail the test, there will be arranged a make-up test. Make-up test can only boost the grade only up to 3.0 (dostateczny).
Make-ups for full grade are permitted only after presenting medical excuse or if earlier absence was caused by unexpected important event or emergency.

9. Contact information
Office:
building D2, room 9b
Websites:

10. Basic definitions

11. Refrigerant is a substance that acts as a cooling agent by absorbing heat from another body or substance. In refrigeration cycle, refrigerant absorb heat at low temperature and low pressure and relase it at higher temperature and pressure.

12. Refrigerants undergo phase transitions:
endothermic - heat absorption (e.g. evaporation, melting, resublimation)
exothermic - heat relase (e.g. condensation, freezing, sublimation, etc.).

13. Any volatile substance which remains liquid at desired temperature of evaporation could be used as refrigerant.

14. The choice of suitable refrigerant is often dictated by various factors including:
temperature and pressure levels in operating conditions,
limitation due to the application, e.g. availability of compressors etc.,
chemical stability, e.g. decomposition at higher temperatures,
ecological directives,
safety factors, e.g. flammability, toxicity,
price, etc.

15. Temperature scale
Different refrigerants are used at different temperature levels.

16. Primary refrigrant
Is used in recirculation cycle (primary refrigeration system).
Utilize latent heat - there are phase changes among thermodynamic cycle transitions.
Directly absorb heat from the environment, other substance or area.

17. Secondary refrigerant
Is used as heat transfer medium - cooled or heated by primary refrigeration system.
Use sensible heat - It is not subjected to the change of phase. Adding or removing heat will cause temperature change.
Is used as heat transfer medium, especially if cooling effect is distributed over a long distance e.g. using fan-coils.

18. Primary and secondary refrigerants
C - circulating refrigerant (e.g. R134a, R410A, CO2, NH3, etc.)
B - secondary refrigerant that assists cooling (e.g. chilled water, brine or air)
D - secondary refrigerant that assists heat removal (e.g. usually water or air)

19. HISTORY OF REFRIGERANTS

20. Overview
The ancient times…
XIXth century and till 1930  (the invention of refrigeration as we know it )
1930 – 1986  (Invention and development of synthetic refrigerants, all the way to the „Ozone Crisis” )
1986 – now  (Global Warming and its consequences )
Now – Someday in the future…  demand for the new generation of refrigerants

21. Read entire paragraph "Refrigerant progression” in Calm J. M
Read entire paragraph "Refrigerant progression” in Calm J.M., The next generation of refrigerants – Historical review, considerations, and outlook., Int. J. of Ref., Volume 31, Issue 7, November 2008, Estimated reading time minutes.

22. Four generations of refrigerants
Calm J.M., The next generation of refrigerants – Historical review, considerations, and outlook., Int. J. of Ref., Volume 31, Issue 7, November 2008,

23. Ancient times
The concept of refrigeration goes back to ancient times when ice and snow were often stored for later use, first experiments with vaporization of water took place or natural underground cold streams were used for air-conditioning of buildings.

24. Qanat
An ancient Iranian windcatcher and qanat, used for evaporative cooling of buildings 

25. First generation (from the beginning of XIXth century till 1930s)
Oliver Evans proposed the use of a volatile fluid in a closed cycle to freeze water into ice in 1805.
He described a system that produced refrigeration by evaporating ether (diethyl ether) under a vacuum, and then pumped the vapor to a water-cooled heat exchanger to condense for re-use. There is no record that he ever built a working prototype.

26. Jacob Perkins invented and built the vapor-compression machine in the 1830s, and thus introduced actual refrigerants as we know them. His 1834 patent describes a cycle using a “volatile fluid for the purpose of producing the cooling and freezing … and yet at the same time condensing such volatile fluids, and bringing them into operation without waste”.
Many refrigeration experts recognize his landmark contribution by calling mechanical vapor-compression approach as the Perkins Cycle.

27. Original Perkins invention as described in his patent (1834).
The refrigerant (ether or other volatile fluid) boils in evaporator B taking heat from surrounding water in container A. The pump C draws vapour away and compresses it to higher pressure at which it can condense to liquids in condenser tubes D, giving out heat to water in vessel E. Condensed liquid flows through the weight loaded valve H, which maintains the difference of pressure between the condenser and evaporator. The small pump above H is used for charging the apparatus with refrigerant.

28. Original Perkins invention recostructed for museum purposes.

29. Read entire paragraph 5 "Liquefiable vapor compression systems using ether" in Reif-Acherman S., The early ice making systems in the nineteenth century., Int. J. of Ref., Volume 35, Issue 5, Pages Estimated reading time minutes.

30. Second generation (1930s s) The shift to fluorochemicals for safety and durability. Thomas Midgley, Jr., and his associates Albert L. Henne and Robert R. McNary first scoured property tables to find neither toxic nor flammable chemicals with the desired boiling point.

31. Thomas Midgley Jr. ( )
An American chemist who developed chlorofluorocarbons (CFCs).
He held over a hundred different patents.

32. While praised for his discoveries during his time, today his legacy is seen as far more mixed considering the serious negative environmental impacts. Midgley "had more impact on the atmosphere than any other single organism in Earth's history."

33. Midgley used systematic approach and eliminated refrigerants that:
yield insufficient volatility i.e. difficult to evaporate
are the inert gases (based on their low boiling points).
result in unstable and toxic compounds,

34. Just eight fundamental elements remained:
carbon
nitrogen
oxygen
sulfur
hydrogen…
and halogens:
fluorine
chlorine
bromine.

35. In 1928, Midgley noted that every known refrigerant at the time combined just seven of these elements – all but fluorine. First publication on fluorochemical refrigerants shows how variation of the chlorination and fluorination of hydrocarbons influences the boiling point, flammability, and toxicity. Commercial production of R-12 began in 1931 followed by R-11 in Chlorofluorocarbons (CFCs) and later hydrochlorofluorocarbons (HCFCs) dominated the second generation of refrigerants.

36. Third generation (1990s s) The discovery that released CFCs – including CFC refrigerants – cause depletion of the protective stratospheric ozone catalyzed development of the third generation focused ozone layer protection. The Montreal Protocol forced the abandonment of ozone-depleting substances (both production and use). This sparked interest in chlorine-less refrigerants (HFCs) along with the expanded use of systems not using vapor-compression (absorption and adsorption).

37. Fourth generation (2010s - now) Renewed interest in natural refrigerants that were dismissed at the beginning of the twentieth century as unsafe and dangerous.

38. Ammonia remained as the refrigerant of choice in industrial systems and especially for food and beverage processing or storage, which often require large internal volumes and flexibility in system modification.
Carbon dioxide use in the low stage of cascaded systems for industrial refrigeration is now common, though it primarily displaces ammonia use in this application.
Water continues as the primary refrigerant in large absorption chillers and chiller heaters, primarily those using lithium bromide as the absorbent.
Air and hydrocarbons.