1. Basic Refrigeration

2. Star Refrigeration Wednesday 12 September 2007

3. AgendaAM Refrigeration basics Simple systems The refrigerant The evaporator The condenser

4. Agenda - continued PM PM The compressor The compressor The expansion device The expansion device Star designs Star designs - LPR - LPR - RCD - RCD - Indigochiller - Indigochiller - CO2 sytems - CO2 sytems

5. Simple Refrigeration System Condenser Compressor Expansion Device Work In Evaporator Heat In Heat Out High Pressure Liquid Low Pressure Liquid & Vapour Low Pressure Vapour High Pressure Vapour

6. Basic Physics WATER (or Refrigerant) Fundamental “STATES” Solid Liquid Vapour (Apply heat) (Remove heat) (WATER)(ICE)(STEAM) (ICE)(WATER)(STEAM)

7. Basic Refrigeration Vapour Compression Cycle In the Evaporator (Evaporation) In the Evaporator (Evaporation) Liquid Vapour Liquid Vapour In the Condenser (Condensation) In the Condenser (Condensation) Liquid Vapour Liquid Vapour (Apply heat) (Remove heat)

8. Heat Transfer Hot Always Hot Always Goes To Cold Heat from the product will migrate to the colder refrigerant THE REFRIGERANT WILL BOIL - EVAPORATION THE REFRIGERANT WILL LIQUEFY - CONDENSATION

9. Heat Transfer : Examples of Evaporation  At 100 o C Water will boil.  The energy the water uses to boil in the kettle is heat from the electric element.  The energy a refrigerant uses to boil in the evaporator is heat from the product.

10. Heat Transfer: Examples of Condensation Steam will condense on kitchen tiles – heat transfer from hot steam to colder tile. Steam will condense on kitchen tiles – heat transfer from hot steam to colder tile. A refrigerant will condense when it is exposed to a medium at a lower temperature, such as water or air. A refrigerant will condense when it is exposed to a medium at a lower temperature, such as water or air.

11. Second Law of Thermodynamics 2 nd Law of Thermodynamics States: “Heat cannot of itself pass from one body to a hotter body” Need to do work to compress this refrigerant gas RRefrigeration cycle needs A Compressor A Condenser An Expansion Device An Evaporator A Refrigerant A pressure – enthalpy (P-H) diagram is a useful device to understand what is happening in the cycle

12. The Refrigerant In a refrigeration system, the working fluid is the Refrigerant. In a refrigeration system, the working fluid is the Refrigerant. Different refrigerants have different boiling temperatures – well below that of water! For example Ammonia will boil at –33 o C (at atmospheric pressure). Different refrigerants have different boiling temperatures – well below that of water! For example Ammonia will boil at –33 o C (at atmospheric pressure).

13. Saturation Temperature

14. Examples of Refrigerants R22: Currently being phased out because of its Ozone Depleting Potential (ODP). Ammonia: Star’s preferred refrigerant. Good refrigerating properties. Zero ODP and Zero Global Warming Potential (GWP) CO2: “Back to the Future”. Excellent refrigerating properties, where appropriate. Zero ODP. GWP = 1. properties, where appropriate. Zero ODP. GWP = 1.Also: New HFC synthetic Refrigerants – R134a, R404A, R407C Zero ODP but High GWP R410A, etc.

15. Typical Star Refrigeration System Compressor(s) Evaporator(s) CondenserExpansion Device

16. Heat Transfer The units for heat energy transferred in the refrigeration system for each kg of refrigerant flowing in the circuit is referred to as the refrigerating effect and has units in kiloJoule/kg (kJ/kg). One kJ/s is equal to one kiloWatt (kW)

17. Summary Star design and build very efficient customised refrigeration plant going into several industrial sectors Star design and build very efficient customised refrigeration plant going into several industrial sectors

18. Star Refrigeration design systems that give maximum refrigeration energy for minimum electrical energy input required to run the plant. Star Refrigeration design systems that give maximum refrigeration energy for minimum electrical energy input required to run the plant. Star plant is : Star plant is : ENERGY EFFICIENT ENERGY EFFICIENT