Evidence shall show that knowledge has been acquired of safe working practices and designing commercial refrigeration systems. All knowledge and skills detailed in this unit should be contextualised to current industry practices and technologies. KS01-EJ132A Commercial refrigeration system design Evidence shall show an understanding of commercial refrigeration system design, applying safe working practices and relevant Standards, Codes and Regulations to an extent indicated by the following aspects: T1. Food spoilage and possible causes physical damage animal activity chemical breakdown enzyme activity micro-organisms effects of temperature change effects of humidity change effects of freezing on fresh produce effects of slow freezing time effect of refreezing T2. Food preservation removing or taking out a reactant removing or inactivating the catalyst reducing temperature changing the reaction system irradiation T3. Micro-organisms conditions for growth potentially hazardous foods cross contamination T4. Identification of food spoilage recognition and suggest possible cause physical damage animal activity chemical breakdown enzyme activity micro - organisms T5. Types of heat processing techniques heat processing using steam and water blanching pasteurisation sterilisation evaporation heat processing using hot air dehydration baking and roasting T6. Types of chilling processing techniques chilling and controlled atmosphere storage freezing freeze drying and freeze concentration modified atmosphere combined with low temperature cryovac. T7. Relevant Standards, Codes, Regulations and industry practices Standards and Codes Regulations Equipment manufactures specifications and practices KS02-EJ132A Refrigeration system components and piping selection Evidence shall show an understanding of refrigeration system components and piping selection, applying safe working practices and relevant Standards, Codes and Regulations to an extent indicated by the following aspects: T1. Relevant Standards, Codes Regulations and industry practices AS1677, detailed understanding AS 3666, overview ozone protection regulations IIAR Ammonia Data Book ANSI/IIAR standards ANSI/ASHRAE Mechanical Refrigeration and IIAR bulletins and standards Equipment manufactures specifications and practices T2. Calculation of capacity in heat exchangers Q = UA (LMTD) Q = mc∆t Q = m ∆h T3. 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 T4. Condensers commercial types and applications effects of ambient conditions condenser control heat rejection factor condenser TD selection criteria and selection tables T5. 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, medium and low back pressure compressors selection tables, motor selection T6. Liquid expansion devices types, operation and applications effects from sub-cooling distributor types, operation and applications selection tables System load balance point encompassing: graphical representation Line sizing an 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 T7. Automatic controls fin spacing, suction temp to evaporator suction hot-gas bypass valves electronic control of valves PLC control 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 |