REFRIGERATION, COMPRESSED AIR SYSTEMS & EFFICIENT USE OF ENERGY

1. REFRIGERATION, COMPRESSED AIR SYSTEMS & EFFICIENT USE OF ENERGY

2. Principles of Refrigeration Refrigeration means to COOL AN OBJECT BELOW ITS SURROUNDING TEMPERATURE

3. Vapour Compression Cycle Basic Components of the vapour compression refrigeration system 3 2 • Compressor • Condenser • Throttling Device • Evaporator CONDENSER COMPRESSOR EXPANSION VALVE EVAPORATOR 1 4

4. Vapour Compression Cycle KN/m2 CONDENSER HEAT REJECTION PRESSURE 3 CONDENSATION 2 Pd CONDENSER 3 2 COMPRESSION COMPRESSOR THROTTLING EXPANSION VALVE EVAPORATOR Pe 4 1 1 4 EVAPORATION ENTHALPY KJ/Kg WORK DONE REFRIGERATION EFFECT

5. VAPOUR COMPRESSION CYCLECOMPONENTS

6. REFRIGERANTS • CHLOROFLUOROCARBONS (CFC) • R-11 • R-12 • HYDROCHLOROFLUOROCARBONS (HCFC) • R- 22 • R-123 • HYDROFLUOROCARBONS (HFC) • R-32 • R-125 • R-134a • R-143a • INORGANIC COMPOUNDS • R- 717 • R- 718 • R- 729

7. Unit of Refrigeration The unit of refrigeration is TON OF REFRIGERATION ( TR ) 1 TR = 12’000 Btu/hr BRITISH UNITS 1 TR = 3.517 KW SI UNITS

8. Refrigeration Cycle Efficiency The refrigeration cycle efficiency is known as COEFFICIENT OF PERFORMANCE (COPREF) (COPREF)= Refrigeration EffectKJ/Kg Work Done KJ/Kg (COPHP)= Condenser Heat Rejection KJ/Kg Work Done KJ/Kg

9. Refrigeration Equipment Efficiency The equipment efficiency is given as EER or kW/TR ENERGY EFFICIENCY RATIO (EER) Use for smaller capacity equipment such as Window type & Split type equipment (EER)= CapacityBtu/hr Power Input Watts kW/TR Use for large capacity equipment such as Chillers (kW/TR)= Power Input kW Capacity TR

10. P-h DIAGRAM FOR REFRIGERANT 134a

11. MONTRÉAL PROTOCOL OBLIGATIONS • Face-out of CFC in year 2005 • Introduction of Quota for HCFC in year 2015 • Face-out of HCFC in year 2040

12. ASHRAE Standard 34-1992 Refrigerant Safety Classifications Higher Flammability INCREASING FLAMMABILITY Lower Flammability No Flame Propagation INCREASING TOXICITY Lower Toxicity Higher Toxicity

13. Refrigerant Data & Safety Classifications

14. AMMONIA (NH3) R-717 • In-expensive Refrigerant best suited for industrial use • Higher refrigeration effect 474 Btu/lb, comparison; R-12 = 50 Btu/lb , R-22 = 70 Btu/lb, R-134a = 64 Btu/lb, R-404A = 48 Btu/lb 7- times higher refrigeration effect!!! • Specific volume of suction gas is high 8 ft3/lb compare to 1.2 ft3/lb of R-22, needs larger pipes, compressors • Higher delivery temperatures 210 ºF, needs water cooled heads for compressor

15. COOLING TOWER (CT)INDUCED DRAUGHT

16. COOLING TOWER (CT)CROSS FLOW

17. COOLING TOWER (CT)FORCED DRAUGHT

18. WATER PUMPSVERTICAL IN-LINE

19. FAILURESDETECTION OF SIMPLEFAILURES • Refrigeration Plant should function properly, if the following checks are OK. • At a glance • Suction sweat • Warm liquid line & clear sight glass from bubbles • Condenser outlet air warm • Condenser water in & out has significant feel of temp deference • Using measuring equipment • Manifold Gauge Set - measure the pressure of refrigerant • Clip-on Ammeter - measure the current flow and voltage • Sling Psychrometer - measure the dry bulb & wet bulb temp. • Anemometer - measure the air flow

20. FAILURESDETECTION OF SIMPLEFAILURES …cont. Detection by observation - A/C unit malfunction if the following observations are found • Sweating down stream of the Filter/dryer – Filter Block • Ice build up at compressor – Over Charge, damaged comp. valves • Ice build up at evaporator – Under charge, gas leak, air filter clogged, cooling coil blocked, fan belts are loose • Bubbles in the sight glass- lack of refrigerant or blocked filter/drier • Oil drops near refrigerant pipe fittings, components etc. – Refrigerant leaks in the system. • Condenser shell cooler & evaporator shell warmer (Centrifugal Chiller) – at low condensing temperatures, refrigerant migrates to evaporator

21. COMPRESSED AIR SYSTEMS

22. Compressed air system provides…….. • Provides air under compression to pneumatic drives • Use reciprocating or screw compressors with storage receiver • Use pressure regulators at the air user point to reduce the air pressure • Use water separators to prevent water vapour entering the air user equipment

23. ROTARY SCREW COMPRESSORS • Pulsation free air • 100% continuous duty • Quiet operation • Energy efficient at full load • Extended service intervals • Reliable long life • Improved air quality

24. TIPS FOR COMPRESSED AIR SYSTEMS • Locate the compressor closest to the largest air user to reduce pressure drop through the air line • Ventilate the compressor well • Keep 3 feet around the compressor unit • Surrounding temperature should be below 115 ºF • Avoid extreme humidity • Keep air filters clean all the time • Use refrigerated and desiccant dryers to reduce water vapour concentration

25. EFFICIENT USE OF ENERGY Resources are limited and conserve energy Refrigeration • Reduce heat transfer • Select energy efficient equipments Compressed air systems • Fix all leaks in the piping • Regulate lowest pressure at air user • Reduce blow-offs • Shut-off air supply to off-line air users • Consider multi staged compressors

26. THANK