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19
APPENDIX B
19.1
List of additional measurements
MEASURE
DEFINITION
λ
, n
Air index
(defined as
λ
, also shown as
n
).
e
Air excess.
Expressed as a percentage according to the formula in the appendix B, is the ratio between the
volume of air actually entering the combustion chamber and the one theoretically needed.
Δ
T
Differential temperature:
This is the difference between the smoke temperature and the temperature of the combustion air.
Qs (PCI)
Loss in chimney with reference to the Lower Heating Value:
It is the percentage of heat lost in the chimney flue in relation to the lower calorific value (PCI).
Qs (PCS)
Loss in chimney with reference to the Higher Heating Value:
It is the percentage of heat lost in the chimney flue in relation to the gross calorific value (PCS).
η
s (PCI)
Sensible efficiency in relation to the Lower Heating Value:
This is the combustion efficiency calculated according to the requirements of UNI 10389-1, as the ratio
between conventional thermal power and thermal power in the fireplace. In terms of losses, only the sensible
heat lost in the chimney flue is taken into consideration, ignoring losses due to radiation or incomplete
combustion. It refers to the Lower Heating Value (PCI) of the fuel and cannot exceed 100%. Sensible
recovery efficiency is the value that must be compared with the minimum efficiencies set out in the
performance verification of thermal systems.
η
s (PCS)
Sensible efficiency in relation to the Higher Heating Value:
This is the combustion efficiency calculated according to the requirements of UNI 10389-1, as the ratio
between conventional thermal power and the thermal power of the fireplace. In terms of losses, only the
sensible heat lost in the chimney flue is taken into consideration, ignoring losses due to radiation or
incomplete combustion. It refers to the Higher Heating Value (PCS) of the fuel and cannot exceed 100%.
Sensible recovery efficiency is the value that must be compared with the minimum efficiencies set out in the
performance verification of thermal systems.
η
c (PCI)
Condensation efficiency in relation to the Lower Heating Value:
Efficiency deriving from the condensation of water vapour contained in the flue gases and calculated
according to the indications of the UNI 10389-1 standard relating to PCI.
η
c (PCS)
Condensation efficiency in relation to the Higher Heating Value:
Efficiency deriving from the condensation of water vapour contained in the flue gases and calculated
according to the indications of the UNI 10389-1 standard relating to PCS.
η
t (PCI)
η
t =
η
s +
η
c
Total efficiency in relation to the Lower Heating Value:
is the result of the sum of the sensible efficiency and the condensation efficiency. It refers to the Lower
Heating Value and may not exceed 100%.
