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Examples

MoistAirTab™ Example 2 - Mixing Streams

Example 2

A stream of 2 m³/s of outdoor air at 4°C dry-bulb temperature and 2°C wet-bulb temperature is mixed with 6.25 m³/s of recirculated air at 25°C dry-bulb and 50% relative humidity. What is the dry-bulb, wet-bulb temperatures and relative humidity of the mixed stream?

Solution

The solution is presented below as a table generated from Excel. The gray shaded areas represent the input data.

Soution:	Units	Steam-1	Stream-2	Mixture
Total pressure	bar	1.01325	1.01325	1.01325
Moist air volumetric flow rate	m³/s	2.00	6.25	8.25
Dry bulb temperature	°C	4.00	25.00	19.67
Wet bulb temperature	°C	2.00	17.88	14.58
Relative humidity	%	71%	50%	58%

Obtain the mixed stream's humidity ratio:
Specific volume (dry air)	m³/kg_{dry air}	0.7848	0.8444	0.8293
Mass flow rate (dry air)	kg_{dry air}/s	2.55	7.40	9.95
Humidity ratio	kg_w/kg_{dry air}	0.0036	0.0099	0.0083
Moisture flowrate	kg_w/s	0.01	0.07	0.08

Obtain the mixed stream's specific humidity:
Specific enthalpy of moist air	kJ/kg_{dry air}	12.97	50.42	40.83
Enthalpy flow	kJ/s	33.06	373.20	406.26

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MoistAirTab™ Example 2 - Mixing Streams

Example 2

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