When boiling food the cooking temperature is limited to about 100° C. Pressure cookers allow for faster cooking by increasing the boiling temperature of water using increased pressure. The pressure within the sealed cooker can be varied by using different weights to seal the vent. A pressure cooker containing 4kg of water is to be used to cook potatoes at 150° C determine (a) what pressure is necessary to maintain the desired boiling temperature and (b) the mass of the weight that must be used in order to maintain the pressure determined in part (a) given a round vent with a diameter of 1cm, (c) if the pressure cooker has a volume of 10L what is the quality of the steam within the pressure cooker the instant it reaches temperature, before any steam is vented (assuming all air has been purged from the cooker by this point) , and (d) how long can the potatoes be cooked at the desired temperature before all the water is boiled away if heat is being added to the system by a 7000 Watt burner.
When boiling food the cooking temperature is limited to about 100° C. Pressure
cookers allow for faster cooking by increasing the boiling temperature of water using increased pressure. The pressure within the sealed cooker can be varied
by using different weights to seal the vent. A pressure cooker containing 4kg
of water is to be used to cook potatoes at 150° C determine
(a) what pressure
is necessary to maintain the desired boiling temperature and
(b) the mass of
the weight that must be used in order to maintain the pressure determined in
part (a) given a round vent with a diameter of 1cm,
(c) if the pressure cooker
has a volume of 10L what is the quality of the steam within the pressure cooker
the instant it reaches temperature, before any steam is vented (assuming all
air has been purged from the cooker by this point) , and
(d) how long can the
potatoes be cooked at the desired temperature before all the water is boiled
away if heat is being added to the system by a 7000 Watt burner.
vf = 0.00109 m3/kg
vfg
= 0.39136 m3/kg
h = 2113.7 kJ/kg
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