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EMPTY BIN TREATMENTS Mimoun Abaraw
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Heat Loss Calculations
Required BTU Surface Area Wall Composition Delta Temperature Natural Infiltration Ventilation Load When calculating Heat Loss there are three different factors that need to be calculated: Required BTU to Heat a Room or Facility How much heat you need to heat-up the structures surfaces to insulate against colder air difference and to achieve your desired temperature. Natural Infiltration Air being drawn into the building due to the pressure imbalance from adding heat Ventilation Load Amount of CFM needed to adequately heat-up room or facility and counter the natural infiltration affect.
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Rectangular Shape Walls Roof Floor 2 x Height x Width (Width)
2 x Height x Length (Length) Roof Width x Length Floor When calculating the BTU’s necessary to heat-up a room or facility you have to figure out the total surface area, that being the Roof, Ceiling and Walls.
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Cylindrical Shape Cylinder R x H x 2 x π Top Plate R² x π Bottom Plate
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Wall Composition Different construction material have different “U Values”. Concrete The next step is to define the different wall compositions so that you can figure its U Value. Define: U Value - Transmission heat loss, expressed in BTU’s-per-square foot of exposed surface. This allows you to figure how much heat is going to be lost through the surfaces so that you can compensate with more heat to reach your desired temperature. Some of the materials will transmit heat faster than others, so there will be a higher heat loss, which is calculated by using a higher “U Value”, this creates more BTU’s per-square-foot. This is also true for vise versa. U Value: Transmission heat loss, expressed in BTU’s-per-square-foot of exposed surface. Metal
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Temperature Difference
ΔT = IT - OT = TD 120o (IT) 50o (OT) ΔT = 120o - 50o = 70o The 3rd step is to figure the Delta “T” Define: Delta “T”: The difference in the outside design temperature and the inside design temperature. This allows you to figure how much heat is going to be needed to compensate for the natural infiltration and the additional heat needed to heat-up the surfaces to the DT. Find the outside design temperature for the location by accessing ASHRE for temp. ΔT: The difference in the outside design temperature (OT) and the inside design temperature (IT).
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Natural Infiltration Air is drawn into a facility because of the pressure imbalance caused by the imbalance in temperature Each room or facility has its own pressure balance, positive and negative. Warm air carries a positive pressure because it is less dense, while cooler or cold air carries a negative pressure because it is more dense. That is why hot air is located at the top of a room and rises. When heat is introduced into a room the warmer air displaces the cooler air, thus creating an imbalance. When this imbalance occurs , natural forces kick-in and draw the cooler air into the room or facility to try and reinstate the natural balance. This will most naturally occur through the openings in the structure such as the cracks, open areas or through the more porous construction material. As you can see here...
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Ventilation Load The amount of CFH, or Air Flow, needed to heat-up the area to the target temperature and displace or control the natural infiltration in an hours’ time. Define: Ventilation Load - The amount of CFH, or Air Flow, needed to heat-up the area to the target temperature and displace or control the natural infiltration in an hours time. By using high CFH heaters with outside air, you induce hot air into the building creating a positive pressure. Balloon Example This affect allows us to control the natural infiltration into a building making maintaining an even heat distribution possible.
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Other Factors to Consider
Air Changes The amount of fresh air that circulates within a facility Ideal air changes are per hour Ductwork Length Ductwork creates static pressure in distributing the heat This draws on the CFM or Air Flow of the heat Negatively affects required CFM and heat discharge You now know what it takes to heat-up a single room or facility, but there are some other considerations that need to be taken to make sure that you, one reach the desired temperature and two have an even heat distribution. Machinery: You want to figure this into your equation because this is where bugs lie. Air Changes: If you fall below 5 to 8 air changes you would like to increase the CFM to assure control of natural infiltration and create adequate heat distribution. Ductwork:
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Using Top Opening Use ductwork with holes inside the bin for better heat distribution When calculating the BTU’s necessary to heat-up a room or facility you have to figure out the total surface area, that being the Roof, Ceiling and Walls.
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Using Bottom Opening No need for ductwork inside the bin
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Temperature Monitoring
130° Temperature Monitoring Thermocouple Use same length as the depth of the bin When calculating the BTU’s necessary to heat-up a room or facility you have to figure out the total surface area, that being the Roof, Ceiling and Walls.
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Any Questions?
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