For the object Coil:Cooling:DX:SingleSpeed â??The rated air volume flow rate should be between .00004027 m3/s and .00006041 m3/s per watt of rated total cooling capacityâ??.
Since dQ/dt = rho * dV/dt * c * DT , a condition regarding the volume flow rate / cooling power ratio (dV/dt) / (dQ/dt) can be expressed as a condition regarding the temperature difference DT.
I consider rho * c = 1206 J / (m^3 * K)
If (dV/dt) / (dQ/dt) = 0.00004027 m3/s / W then DT = 21 K
If (dV/dt) / (dQ/dt) = 0.00006041 m3/s / W then DT = 13,7 K
Therefore the temperature difference between inlet temperature and outlet temperature must be between 13,7 K and 21 K.
Why such a condition?
I have to model a split with 0,13 m^3/s and 4000 W, therefore the ratio is 3,25*10^(-5) m^3/s / W and it isn't acceptable.
I get the following error:
** Severe ** Sizing: Coil:Cooling:DX:SingleSpeed "0TERRA:LOCMACCHINETTE PTHP DX COOLING COIL": Rated air volume flow rate per watt of rated total cooling capacity is out of range.
** ~~~ ** Min Rated Vol Flow Per Watt=[4.027E-005], Rated Vol Flow Per Watt=[3.250E-005], Max Rated Vol Flow Per Watt=[6.041E-005]. See Input Output Reference Manual for valid range.
** Severe ** For object = Coil:Cooling:DX:SingleSpeed, name = "0TERRA:LOCMACCHINETTE PTHP DX COOLING COIL"
** ~~~ ** Calculated outlet air relative humidity greater than 1. The combination of
** ~~~ ** rated air volume flow rate, total cooling capacity and sensible heat ratio yields coil exiting
** ~~~ ** air conditions above the saturation curve. Possible fixes are to reduce the rated total cooling
** ~~~ ** capacity, increase the rated air volume flow rate, or reduce the rated sensible heat ratio for this coil.
** ~~~ ** If autosizing, it is recommended that all three of these values be autosized.
** ~~~ ** ...Inputs used for calculating cooling coil bypass factor.
** ~~~ ** ...Inlet Air Temperature = 26.67 C
** ~~~ ** ...Outlet Air Temperature = 8.51 C
** ~~~ ** ...Inlet Air Humidity Ratio = 1.125000E-002 kgWater/kgDryAir
** ~~~ ** ...Outlet Air Humidity Ratio = 7.773262E-003 kgWater/kgDryAir
** ~~~ ** ...Total Cooling Capacity used in calculation = 4000.00 W
** ~~~ ** ...Air Mass Flow Rate used in calculation = 0.146115 kg/s
** ~~~ ** ...Air Volume Flow Rate used in calculation = 0.130000 m3/s
** ~~~ ** ...Air Volume Flow Rate per Watt of Rated Cooling Capacity is also out of bounds at = 3.2500000E-005 m3/s/W
** ~~~ ** During Warmup, Environment=BOLZANO ANN HTG 99.6% CONDNS DB, at Simulation time=01/21 00:00 - 00:10
** Fatal ** Check and revise the input data for this coil before rerunning the simulation.
What shall I do?