# Calculating pasteurisation & equilibrium pressure of CO2 in water

Overview
1. Calculation of equilibrium pressure (dissolving power) of CO2 in water.
2. Calculation of the Pasteur units (PU)
3. Holding cell (heat retention unit) calculation
4. Calculation of heat recovery

The essential parameters of pasteurisation plants for beverages can be determined or recalculated with the calculation programmes made available here. The focus is on flash pasteurisation plants here as they form part of our product range. A few calculations are however generally applicable and they can also be used for tunnel pasteurisers and pasteurisation cabinets.

1. Calculation of equilibrium pressure (dissolving power) of CO2 in water:
=>Calculation of equilibrium pressure in the range from 0.1°C to 30°C and max. 15g/litre, approximately
CO2-content [grams per litre]:
g/l

Temperature:
°C

Result [bar]

=> Calculation of equilibrium pressure in the range from 40°C to 80°C and max. 15g/litre, approximately

CO2-content [grams per litre]:
g/l

Temperature:
°C

Result [bar]

If a carbonated drink is exposed to temperature treatment, the temperature treatment must occur under pressure so that the CO2 (carbon dioxide) does not discharge itself (dissolved CO2 gas in water). The minimum amount of pressure required can be established with the accompanying calculation programme. However, it must be taken into account that mechanical effects also lead to CO2 discharge. If the required pressure (equilibrium pressure) for a fluid medium (e.g. in the constant heat unit of a flash pasteuriser) is to be calculated, a safety margin must be applied. The calculation refers to the solubility of CO2 in water but it can also be used as an approximation for beverages (beer, alcohol free beverages etc.). The solubility for CO2 is higher in mixed drinks than in water.

The CO2 content in grammes per litre must be entered in the accompanying input field. If the CO2 content is given as a percentage, a simple conversion must take place: 0.6% = 6g/litre.

In the USA the CO2 content is often indicated with a dimensionless volume unit: 6g/litre=3.2volumes; 5g/litre=2.55 volumes. The volume indication can thus be multiplied by the factor 2 and then used in the accompanying calculation programme.

2. Calculation of the Pasteur units (PU)
=> PU calculation for fruit juice

Holding time:
min

Temperature:
°C

Result [ PE ]

The calculation formulae shown here for establishing the Pasteur units for beer, fruit juice and beverages containing fruit juice are generally used to make a uniform understanding regarding pasteurisation possible. It must however be taken into account that the calculation formulae were established with the assistance of series of tests. Series of tests with different test media also lead to varying outcomes. In US references, there are different formulae which are very likely to result in different outcomes.

PU calculation for fruit juice

PU = time * 1.2589^(temperature-80)

=> PU calculation for beer

Holding time:
min

Temperature:
°C

Result [ PU ]

PU calculation for beer

PU = time * 1.393^(temperature-60)

3. Holding cell (heat retention unit) calculation:
=> Holding cell calculation
Holding [seconds]:
s

Pipe diameter [mm]:
mm

Volumic flow rate [hectolitre (100 litres) per houre]:
hl/h

Result

Lh = lengt holding cell [m]
w = flow speed rate [m/s]
VL = content holding cell [litre]

4. Heat recovery [%]:
=> Heat recovery rate
T1 [°C]:
°C

T2 [°C]:
°C

T3 [°C]:
°C

Result [%]

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