How to calculate the Latent Load for laundry area and its equipments generating steam?

For sure we have to get appliances data from the suppliers but in such cases we have to estimate the latent load value, i found many sources as following:

*ASHRAE Fundamentals 2013 CH 18

NONRESIDENTIAL COOLING AND HEATING LOAD CALCULATIONS 

Table 5E Recommended Rates of Radiant and Convective Heat Gain from Warewashing Equipment

During Idle (Standby) or Washing Conditions

* Carrier hand bock CH. 7 load estimating , internal and system heat gain

TABLE 52-HEAT GAIN FROM MISCELLANEOUS APPLIANCES NOT HOODED

*Fundamentals of Heating, Ventilating, and Air-Conditioning

 QBlatentB = 2500 ρ VBflowB (WBoB - WBiB)

where

ρ = air density

VBflowB = ventilation or infiltration flow rate (Thermal comfort & IAQ requirements)

WBoB, WBiB = outside, inside air humidity ratio

*Handbook of Air Conditioning and Refrigeration 2nd ed. - S. Wang (2001)

 The latent heat gain from the equipment and appliances ql,e, Btu /h (W), can be calculated from

the mass flow rate of water vapor evaporated , as

ql,e = 1075 m˙w

m˙w in  lb / h or (kg / h)

Normally the latent load in Laundry is due to steam or water from washer and extractors or iron.

These equipments are normally provided with exhaust  so that most of the latent heat is exhausted, However the steam consumption from the equipment can be considered b ytheir catalouge and by steam tables the energy in those stem or vapors can be calculated and by enthalpy difference of two states total load and humidity difference exact laten load can be found

supply of fresh air and ducted exhaust fan

As Per ASHRAE Application 2015, Page 52.13

Cooling Laundries

Laundries have one of the most severe environments in which

direct evaporative air cooling is applied because heat is produced

not only by the processing equipment, but by steam and water vapor

as well. A properly designed direct evaporative cooler reduces the

temperature in a laundry 3 to 6 K below the outdoor temperature.

With only fan ventilation, laundries usually exceed the outdoor temperature

by at least 5 K. Air distribution should be designed for a

maximum throw of not more than 9 m. A minimum circulated

velocity of 0.5 to 1 m/s should prevail in the occupied space. Ducts

can be located to discharge the air directly onto workers in exceptionally

hot areas, such as pressing and ironing departments. For

these outlets, there should be some means of manual control to

direct the air where it is desired, with at least 250 to 500 L/s at a target

velocity of 3 to 4.5 m/s for each workstation.

The main sources of latent loads are infiltration, perspiration and exhalation by occupants, cooking, laundry, showering, and bathing.

Although some sources assume that a home’s latent load is 30% of the total load, the actual latent load varies widely; it depends on a home’s infiltration rate, the climate, and the amount of moisture generated by occupants. For leaky homes in hot, humid states like Louisiana, the latent load can be higher than 30% of the total load. Conversely, homes located in arid states west of the Rocky Mountains usually have latent loads that are much less than 30% of the total load.

The sensible load divided by the total load (including the latent load) is called the sensible heat ratio (SHR) or sensible heat factor (SHF). The cooling load calculation method used by Manual J (the most common calculation method) assumes a default value of 0.75 for the sensible heat ratio; however, software programs allow users to enter a different SHR if they prefer. Most air conditioning equipment is designed to operate at a sensible heat ratio in the range of 0.70 to 0.75.

According to ASHRAE Fundamentals, “A latent factor (LF = 1/SHF) of 1.3 or a sensible heat factor (SHF = sensible load/total load) of 0.77 matches the performance of typical residential vapor compression cooling systems. Homes in almost all other regions of North America have cooling loads with an SHF greater than 0.77 and latent factors less than 1.3.”

it depends on the the heat dissipation by each machine in watt (which u can get it by catalouge of that particular machine model) and no of people working in that particular laundry area  plus the heat dissipation by vaporize steam and   + factor of safety . based on all that parameters value u ill get the fresh air  CFM required  in that particular area.

you can check the heat release from the factory catalog  

The manufacturer shall provide you with the projected latent load for the laundry equipment, add 15% safety factor then add the total latent load to the programme that you are using to calculate the heat load

components catalougue is sufficient to get the required data on top of that u can refer to ashrae standards

Good day Mr. Siddiqui, have a pleasure in answering your question.

Hope this type of question comes from the consultant side if I am not wrong. Generally the manufacturer recommended specifications and ratings are available for the laundry and kitchen equipment. The sensible, latent heat and the fresh air requirements shall be clearly provided as manufacturer's recommendations. To add a safety factor above the required parameters for the design.

My general interpretation is the laundary equipment shall be fitted with an ducted exhaust fan to extract the steam to outside.