18 Questions
What is the purpose of adding chlorine to water in a hydrocooling system?
To reduce bacteria build-up in water
What is the advantage of forced-air cooling systems over hydrocooling systems in terms of maintenance?
Simple and easy to maintain, no leakage problems
Why are hydrocooling systems more effective than forced-air cooling systems?
Higher heat transfer coefficients
What is the typical velocity at which refrigerated air approaches the cooling section in forced-air cooling systems?
1.5 to 2 m/s
How can the cooling time of fruits and vegetables be reduced in forced-air cooling systems?
By spacing the product containers to allow airflow throughout
What is the range of convection heat transfer coefficients in forced-air cooling systems?
30 to 60 W/m2 · C
What is the purpose of vacuum cooling in the context of cooling products?
To reduce the pressure in the cooling chamber to lower the product temperature by evaporating water from the products.
What is the significance of the saturation pressure of water at 0°C in vacuum cooling?
The products can be cooled to 0°C by lowering the pressure to the saturation pressure of water at that temperature (0.61 kPa).
Describe the cooling process in the first stage of vacuum cooling.
In the first stage, products at ambient temperature are loaded into the flash chamber, and the temperature remains constant until the saturation pressure is reached.
What happens in the second stage of vacuum cooling after reaching the saturation pressure at 25°C?
Saturation conditions are maintained inside at progressively lower pressures and temperatures until the desired temperature, usually slightly above 0°C, is reached.
How does impingement air cooling work in cooling products?
Impingement air cooling involves products continuously passing through a cooling tunnel on conveyor belts while being cooled by forced air.
What is the purpose of forced air cooling in the context of cut flowers?
Forced air cooling is commonly used to cool cut flowers.
What is the formula to calculate the amount of beef mass that needs to be cooled per unit time?
mbeef = (Total beef mass cooled) / (Cooling time)
What is the total refrigeration load of the chilling room, including beef cooling, fan, lights, and heat gain?
Qtotal, chill room = Qbeef + Qfan + Qlights + Qheat gain
What percentage of the total product cooling load is attributed to evaporative cooling of water?
85 percent
What is the mass flow rate of air when heat is transferred to air causing a temperature rise from -2°C to 0.7°C?
102.0 kg/s
What is the formula to calculate the volume flow rate of air?
Vair = mair / rair
Normally, what is the heat transfer load of the evaporator in comparison to the total refrigeration load of the chilling room?
The same
Explore the process of cooling water in a hydrocooling system used in the food industry. Learn about the benefits of recirculating water, as well as the challenges it poses in terms of preserving microorganisms from fruits and vegetables. Discover the use of chemicals like chlorine to maintain water quality.
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