commercial refrigeration system design, safe working practices and relevant standards, codes and regulations, including: food spoilage and possible causes: physical damage animal activity chemical breakdown enzyme activity microorganisms effects of temperature change effects of humidity change effects of freezing on fresh produce effects of slow freezing time effect of refreezing food preservation: removing or taking out a reactant removing or inactivating the catalyst reducing temperature changing the reaction system irradiation microorganisms: conditions for growth potentially hazardous foods cross-contamination identification of food spoilage: recognition and suggest possible cause physical damage animal activity chemical breakdown enzyme activity microorganisms types of heat processing techniques: heat processing using steam and water blanching pasteurisation sterilisation evaporation heat processing using hot air dehydration baking and roasting types of chilling processing techniques: chilling and controlled atmosphere storage freezing freeze drying and freeze concentration modified atmosphere combined with low temperature cryovac equipment manufactures specifications and practices refrigeration system components and piping selection, safe working practices and relevant standards, codes and regulations, including: relevant industry practices: AS/NZS 1677 Refrigerating systems SAA refrigeration code AS/NZS 3666 Air-handling and water systems of buildings ozone protection regulations IIAR ammonia data book ANSI/IIAR standards ANSI/ASHRAE mechanical refrigeration and IIAR bulletins and standards equipment manufacturer’s specifications and practices calculation of capacity in heat exchangers: Q = UA (LMTD) Q = mc∆t Q = m ∆h evaporators: commercial types and applications coil bypass factor effects of evaporator TD on space humidity effects of air circulation on product conditions selection criteria and selection tables condensers: commercial types and applications effects of ambient conditions condenser control heat rejection factor condenser TD selection criteria and selection tables compressors: types and applications capacity displacement volume flow rate theoretical capacity total volumetric efficiency effect of operating conditions, including suction pressure drop and superheating actual capacity power theoretical requirement effects of operating conditions actual requirements post defrost loads pull down torque requirements, high and medium and low back pressure compressors selection tables, motor selection liquid expansion devices: types, operation and applications effects from sub-cooling distributor types, operation and applications selection tables system load balance point graphical representation line sizing and design velocity tables pressure drop in lines and fittings oil migration stabilisation refrigerant velocity effect of varying system capacity oil traps risers double risers liquid migration design for parallel components and multiplex systems automatic controls: fin spacing, suction temp to evaporator suction hot-gas bypass valves electronic control of valves and programmable logic controllers (PLC) refrigerant regulating valves solenoid valves condenser pressure regulating valves evaporator pressure regulating valves crankcase pressure regulating valves cycling controls pressure-stats thermostats defrost controls monitoring and alarm controls refrigeration automation systems control strategies control modes relevant job safety assessments or risk mitigation processes relevant WHS/OHS legislated requirements relevant workplace budget, quality, policies and procedures relevant workplace documentation. |