UNIT 27 COMMERCIAL ICE MACHINES UNIT OBJECTIVES 1

UNIT 27 COMMERCIAL ICE MACHINES

UNIT OBJECTIVES 1. Describe the refrigeration cycle for flake ice machines 2. Explain the functions of the harvest, flush cycle and bin controls 3. Describe production and performance charts for ice machines 4. Explain how various shapes of ice are produced

5. Explain an ice machine’s sequence of operations 6. Discuss the importance of water quality in the ice making process 7. Discuss the concepts of cleaning, sanitizing and filtration

27. 1 PACKAGED-TYPE ICE MAKING EQUIPMENT 1. Most package ice makers are air cooled , Ice is formed on the evaporator and then harvested 2. Ice is stored in a bin located below the unit at 32 degrees F 3. Melting ice provides the cooling in the bin 4. Water must be supplied to the unit and a drain must be furnished for the bin (Two types: Flake ice & Cube ice)

27. 2 MAKING FLAKE ICE 1. Formed in a vertical cylinder surrounded by the evaporator, use flights as a cutting surface, forms flakes (fig. 27. 1) 2. An auger scrapes the ice from the cylinder walls (fig. 27. 2) 3. Ice is removed and stored in a bin (fig. 27. 3) 4. Water level is critical and maintained by a float on the top of the evaporator (fig. 27. 5)

Reservoir Evaporator Water supply to refrigerated cylinder Rotating auger Ice chute

Ice forms on the inside surface of the refrigerated cylinder

As the auger rotates, the flights scrape the ice, forming flakes Ice flakes in the chute falling into the bin

27. 2 MAKING FLAKE ICE 1. Evaporator and auger surfaces must be clean and free of score marks 2. Auger turns at a speed of 9 to 16 rpm 3. Speed is reduced by a gear reduction drive 4. Gear assembly prone to failure 5. Auger should not wobble 6. Annual equipment cleaning prolongs system life

WATER FILLING SYSTEMS Conductivity probe or water sensor in water reservoir. 1. Water level sensed by the probe 2. Electric water valve opens when the water level is low (fig. 27. 10 a, b)

Water inlet Float valve Water level Reservoir Overflow Water to refrigerated cylinder

MAKING FLAKE ICE – WATER FILL SYSTEM (fig. 27. 11) Dual float switch and water control valve 1. Float switch controls a solenoid valve 2. Solenoid controls the water valve 3. System shuts down if there is a low water situation

FLUSH CYCLES pg. 690 1. Minerals can cause maintenance problems and poor ice quality 2. Periodic flushing helps remove mineral deposits 3. Flushing cycles are often computer controlled 4. Can be automatic or manual 5. Some systems drain whenever system cycles off Note: see (fig. 27. 12) for flush timer, flush switch and flush water solenoid valve.

BIN CONTROLS pg. 690 1. When bin is full, ice-making process must stop 2. Mechanical flapper device senses backed-up ice 3. Infrared electric eye a. Sensors can “see” each other when ice level is low b. When ice builds up, sensors cannot see each other 4. Sonar waves reflected to the control from the ice 5. Thermostats are liquid-filled bulbs

ICE PRODUCTION AND PERFORMANCE DATA (pg. 692) 1. Ice production drops as water temperature increases a. More energy is required to cool and freeze ice 2. Ice production decreases as ambient temperature increases a. More heat gain on the ice (fig. 27. 13)

ICE FLAKE SIZE ADJUSTMENT (pg. 693) 1. More diverse machines 2. Adjustment of the ice cutter 3. Small, medium, or large flakes can be produced 4. Cutting heads can be changed 5. Extrusion heads: cubelet and flaked ice from same machine

27. 3 MAKING CUBE ICE Flat ice cut into cubes (pg. 693) 1. Ice formed on a flat evaporator 2. Ice thickness is sensed and monitored 3. Ice sheet slides onto a wire grid 4. Grid is heated 5. Grid cuts the ice into the desired shape

(fig. 27. 15) Water manifold Water flowing over evaporator Ice Evaporator tubes Pump

MAKING CUBE ICE Cube ice 1. Water is flooded over an evaporator with individual cups 2. Cups are shaped like the cubes 3. Ice is formed and then stored in a 4. Most common are vertical evaporator Eyeglass-shaped ice cubes (fig. 27. 18) 1. Water flows over evaporator by gravity 2. Ice falls out of the cups during harvest or defrost

Evaporator tubes Ice cups (fig. 27. 17 a-e)

Evaporator tubes Water spray Rotating water spray bar

Evaporator tubes Water spray Rotating water spray bar Ice cubes are formed

Hot gas in evaporator tubes for harvest Hot gas frees the ice cubes from the evaporator

MAKING CUBE ICE Crescent-shaped ice cubes (fig. 27. 19) 1. Water runs over evaporator plates 2. As water freezes, the water level drops 3. When water level is low enough, harvest is initiated 4. Hot discharge gas is directed through the evaporator 5. Cubes begin to melt 6. Cubes slide down the plate and into the bin

MAKING CUBE ICE Cell-type ice cubes (fig. 27. 20) 1 Vertical evaporator 2. Water flows over the coil by a water pump 3. Ice will form in the cells, and bridges will form between the cells 4. When correct bridge thickness is obtained, harvest is initiated 5. Water level in reservoir controlled by a float switch or probe

Water distribution tube Water flows over the evaporator Vertical evaporator

Water flows over the evaporator Ice begins to form in each individual cell

Water flows over the evaporator Ice cubes are formed

Bridge thickness sensor (fig. 27. 25 a) Ice cubes in evaporator

Bridge thickness sensor Ice bridge between cubes (fig. 27. 25 a) Ice bridge is sensed by the control

MAKING CUBE ICE Ice harvests 1. Hot discharge gas piped to the evaporator 2. Suction-line accumulators are used 3. Liquid flood back can damage the compressor 4. If water is too pure, harvest may not be initiated 5. Weep holes help separate the ice from the evaporator 6. Dump valve may be energized during harvest 7. Release of ice must be detected

ICE MACHINE PRESSURE CONTROLS (pg. 710) Fan cycling controls opens and closes to maintain desired head pressure High pressure switch (Safety device) 1. Will open if head pressure reaches unsafe levels Low pressure controls 2. De-energize system if suction pressure drops too low Reverse-acting low pressure switches 1. Close contacts on a drop in pressure 2. Used to initiate the harvest cycle

27. 4 MICROPROCESSORS 1. Store the sequence of operations for the system 2. Can perform self-diagnostics 3. Make systems more reliable, easier to troubleshoot and less complicated 4. Small computer, known as integrated circuit controllers 5. Technician should know how to INPUT/OUTPUT troubleshoot using external terminals 6. Microprocessor’s self diagnostics and error codes 7. Microprocessor’s history or summary (fig. 27. 46 a)

27. 5 MAKING CYLINDRICAL ICE 1. Utilizes a tube within a tube evaporator 2. Refrigerant flows in the outer tube, water in the inner tube 3. Ice begins to form and the water tube begins to close up 4. Water pressure begins to increase 5. At a predetermined pressure, harvest is initiated 6. Hot gas is piped to the evaporator 7. Water pressure pushes ice from the tube

Suction gas to compressor Evaporator for making cylindrical ice Metering device

Refrigerant to compressor Water pumped through evaporator Refrigerant to evaporator

Refrigerant to compressor Water flow is restricted as ice forms Ice forms on the inside surface of the tube Refrigerant to evaporator

Refrigerant to compressor Water flow is restricted as ice forms Ice forms on the inside surface of the tube Refrigerant to evaporator

Hot gas for harvest Water flow is restricted as ice forms Ice forms on the inside surface of the tube Harvest is initiated when the pump pressure reaches the predetermined point Hot gas for harvest

Hot gas for harvest Water pressure pushes ice from the tube Cylindrical ice is pushed from the tube Harvest is initiated when the pump pressure reaches the predetermined point Hot gas for harvest

27. 6 WATER AND ICE QUALITY 1. Ice is a food source 2. Quality of ice depends on the quality of the water used 3. Water quality varies greatly a. Sediment b. Scale c. Iron d. Total dissolved solids e. p. H f. Chlorine

ICE QUALITY (pg. 720) 1. Measured in percent of hardness 2. Hardness represents thermal cooling capacity 3. The harder the ice, the more cooling ability the ice has 4. Harder ice is denser and will last longer 5. Calorimeter test to determine ice hardness 6. Cleaner ice machines + Pure water = Hard Ice

SANITIZING AND CLEANING (pg. 721) 1. Helps eliminate bacteria, viruses, and protozoa 2. Airborne organisms are more common than those in the water supply 3. Cleaning solutions are food-grade acids 4. Scale removers and sanitizers should not be used together 5. Once a month for sanitizing

WATER FILTRATION AND TREATMENT (pg. 722) 1. 75% of system problems are water related 2. Water treatment reduces cleaning/sanitizing frequency 3. Suspended solids are easy to remove with mechanical filters 4. Dissolved metals and minerals require RO, distillation, or de-ionization 5. Chemicals are removed with carbon filtration 6. Uses polyphosphates to inhibit calcium or lime scale 7. Always wear eye protection when working with chemicals

27. 7 PACKAGED ICE MACHINE LOCATION 1. Most ice makers are designed to operate in locations that are between 40° and 115°F 2. Outdoor units may not function properly if temperature falls below 40°F 3. Outdoor units often have head pressure controls 4. Indoor units must have enough airflow through the condenser coil

Installation of a package machine Set and level the machine Supply power, plug or hard wire Provide a water supply Provide a drain for ice bin

27. 8 TROUBLESHOOTING ICE MAKERS Water circuit problems 1. Water level is critical and should be properly set 2. Seat on the float valve is a common source for leaking 3. Water can leak in to the bin and melt ice 4. Check float seat for leaks when the bin is empty 5. Follow manufacturer guidelines regarding evaporator water flow 6. Supply water must be of good quality

TROUBLESHOOTING ICE MAKERS High-side pressure problems 1. Poor condenser air circulation 2. Recirculating condenser air 3. Dirty condenser 4. Defective condenser fan motor 5. System overcharge 6. Noncondensables in the system

TROUBLESHOOTING ICE MAKERS Low-side pressure problems 1. Low refrigerant charge or improper water flow 2. Mineral deposits on evaporator 3. Restricted drier or liquid line 4. Defective metering device 5. Moisture in the refrigerant 6. Inefficient compressor 7. Starved evaporator

TROUBLESHOOTING ICE MAKERS Electrical problems Defrost problems 1. larger -than-normal ice shapes (delayed or no defrost) 2. No ice production (harvest will not terminate) 3. No ice production (water pump problems) 4. Improper supply voltage – out of range 5. Overheating of the power cord

SUMMARY - 1 Ice is formed on the evaporator and then harvested Water and drainage must be supplied to the unit Harvested ice is stored in a bin for future use Flake ice is produced by scraping the ice from the evaporator surface with an auger Production and harvest of flake ice are continuous Evaporator water level is maintained by a float switch, conductivity probe or water sensor Periodic flushing helps remove mineral deposits

SUMMARY - 2 When bin is full, ice-making process must stop Rate of ice production drops as the water and ambient temperatures drop Cube ice can be produced as sheets of ice that are cut into cubes or as individual cubes or cells The shape of the cells determine the ice shape Harvesting ice cubes is accomplished with hot gas from the compressor Ice makers use pressure controls to maintain desired system operating pressures and temperatures