Heating Coil - Fuel

Coil:Heating:Fuel

Used in:   Air Handling Units Demand loops of Dual duct systems Air Distribution Units

The fuel heating coil is a simple capacity model with a user inputted burner efficiency. The default for the burner efficiency is 80%. The coil can be used in air loops or in zone equipment as a reheat coil. Depending on where it is used determines whether this coil is temperature or capacity controlled. If used in the air loop simulation it will be controlled to a specified temperature scheduled from the Setpoint manager. If it is used in zone equipment, it will be controlled from the zone thermostat by meeting the zone demand.

Name

A unique identifying name for each coil.

Type

The type of a fuel coil must be:

• 3-Fuel

In all cases it will also be possible to select 2-Electric in which case the Electric heating coil is used or 1-Water where the Water heating coil is used instead.

Fuel

The fuel list is only available in v5.1 and later only.

Select the fuel to be used for supplying heat to the coil from the list:

• 1-Gas,
• 2-Natural gas,
• 3-Propane gas,
• 4-Fuel oil 1,
• 5-Fuel oil 2,
• 6-Diesel,
• 7-Gasoline,
• 8-Coal,
• 9-Steam,
• 10-District heating,
• 11-District cooling,
• 12-Other fuel 1,
• 13-Other fuel 2

Efficiency

This is user inputted burner efficiency (decimal, not percent) and is defaulted to 0.8 (80%).

Parasitic electric load

This is the parasitic electric load associated with the coil operation, such as an inducer fan, etc.. This will be modified by the PLR (or coil runtime fraction if a part-load fraction correlation is provided in the next input field) to reflect the time of operation in a simulation timestep.

Parasitic fuel load

This numeric field is the parasitic fuel load associated with the coil’s operation (in W), such as a standing pilot light. The model assumes that this parasitic load is consumed only for the portion of the simulation timestep where the heating coil is not operating.

Nominal capacity

This is the maximum capacity of the coil (in W). This controlled coil will only provide the needed capacity to meet

Part Load Performance

Part load fraction correlation

Check this option if a part load fraction correlation is to be applied.

Part load fraction correlation curve

The Quadratic or Cubic performance curve selected here parameterises the variation of fuel consumption rate by the heating coil as a function of the part load ratio (PLR, sensible heating load/nominal capacity of the heating coil). For any simulation timestep, the nominal fuel consumption rate (heating load/burner efficiency) is divided by the part-load fraction (PLF) if a part-load curve has been defined. The part-load curve accounts for efficiency losses due to transient coil operation.

The part-load fraction correlation should be normalized to a value of 1.0 when the part load ratio equals 1.0 (i.e., no efficiency losses when the heating coil runs continuously for the simulation timestep). For PLR values between 0 and 1 ( 0 <= PLR < 1), the following rules apply:

PLF >= 0.7 and PLF >= PLR If PLF < 0.7 a warning message is issued, the program resets the PLF value to 0.7, and the simulation proceeds. The runtime fraction of the heating coil is defined a PLR/PLF. If PLF < PLR, then a warning message is issues and the runtime fraction of the coil is limited to 1.0.

A typical part load fraction correlation for a conventional gas heating coil (e.g., residential furnace) would be:

PLF = 0.8 + 0.2(PLR)

Operation

Available schedule

Schedule that defines when the coil is available.