ISO 18125:2017
Solid biofuels — Determination of calorific value
ISO 18125:2017 specifies a method for the determination of the gross calorific value of a solid biofuel at constant volume and at the reference temperature 25 °C in a bomb calorimeter calibrated by combustion of certified benzoic acid.
The result obtained is the gross calorific value of the analysis sample at constant volume with all the water of the combustion products as liquid water. In practice, biofuels are burned at constant (atmospheric) pressure and the water is either not condensed (removed as vapour with the flue gases) or condensed. Under both conditions, the operative heat of combustion to be used is the net calorific value of the fuel at constant pressure. The net calorific value at constant volume may also be used; formulae are given for calculating both values.
General principles and procedures for the calibrations and the biofuel experiments are presented in the main text, whereas those pertaining to the use of a particular type of calorimetric instrument are described in Annexes A to C. Annex D contains checklists for performing calibration and fuel experiments using specified types of calorimeters. Annex E gives examples to illustrate some of the calculations.
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Foreword
1 Scope
2 Normative references
3 Terms and definitions
4 Principle
4.1 Gross calorific value
4.2 Net calorific value
5 Reagents
6 Apparatus
7 Preparation of test sample
8 Calorimetric procedure
8.1 General
8.2 Preparing the bomb for measurement
8.2.1 General procedure
8.2.2 Using combustion aid
8.3 Assembling the calorimeter
8.4 Combustion reaction and temperature measurements
8.5 Analysis of products of combustion
8.6 Corrected temperature rise θ
8.6.1 Observed temperature rise
8.6.2 Isoperibol and static-jacket calorimeters
8.6.3 Adiabatic calorimeters
8.6.4 Thermometer corrections
8.7 Reference temperature
9 Calibration
9.1 Principle
9.2 Calibrant
9.2.1 Certification conditions
9.2.2 Calibration conditions
9.3 Valid working range of the effective heat capacity ε
9.4 Ancillary contributions
9.5 Calibration procedure
9.6 Calculation of effective heat capacity for the individual experiment
9.6.1 Constant mass-of-calorimeter-water basis
9.6.2 Constant total-calorimeter-mass basis
9.7 Precision of the mean value of the effective heat capacity ε
9.7.1 Constant value of ε
9.7.2 ε as a function of the observed temperature rise
9.8 Redetermination of the effective heat capacity
10 Gross calorific value
10.1 General
10.2 Combustion
10.3 Calculation of gross calorific value
10.3.1 General
10.3.2 Constant mass-of-calorimeter-water basis
10.3.3 Constant total-calorimeter-mass basis
10.3.4 ε as a function of the observed temperature rise
10.4 Expression of results
10.5 Calculation to other bases
11 Performance characteristics
11.1 Repeatability limit
11.2 Reproducibility limit
12 Calculation of net calorific value at constant pressure
12.1 General
12.2 Calculations
13 Test report
Annex A (normative) Adiabatic bomb calorimeters
Annex B (normative) Isoperibol and static-jacket bomb calorimeters
Annex C (normative) Automated bomb calorimeters
Annex D (informative) Checklists for the design and procedures of combustion experiments
Annex E (informative) Examples to illustrate the main calculations used in this document when an automated bomb calorimeter is used for determinations
Annex F (informative) List of symbols used in this document
Annex G (informative) Default values of most used solid biofuels for the calculations of calorific values
Annex H (informative) Flow chart for a routine calorific value determination
Bibliography
Index
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Foreword
1 Scope
2 Normative references
3 Terms and definitions
4 Principle
4.1 Gross calorific value
4.2 Net calorific value
5 Reagents
6 Apparatus
7 Preparation of test sample
8 Calorimetric procedure
8.1 General
8.2 Preparing the bomb for measurement
8.2.1 General procedure
8.2.2 Using combustion aid
8.3 Assembling the calorimeter
8.4 Combustion reaction and temperature measurements
8.5 Analysis of products of combustion
8.6 Corrected temperature rise θ
8.6.1 Observed temperature rise
8.6.2 Isoperibol and static-jacket calorimeters
8.6.3 Adiabatic calorimeters
8.6.4 Thermometer corrections
8.7 Reference temperature
9 Calibration
9.1 Principle
9.2 Calibrant
9.2.1 Certification conditions
9.2.2 Calibration conditions
9.3 Valid working range of the effective heat capacity ε
9.4 Ancillary contributions
9.5 Calibration procedure
9.6 Calculation of effective heat capacity for the individual experiment
9.6.1 Constant mass-of-calorimeter-water basis
9.6.2 Constant total-calorimeter-mass basis
9.7 Precision of the mean value of the effective heat capacity ε
9.7.1 Constant value of ε
9.7.2 ε as a function of the observed temperature rise
9.8 Redetermination of the effective heat capacity
10 Gross calorific value
10.1 General
10.2 Combustion
10.3 Calculation of gross calorific value
10.3.1 General
10.3.2 Constant mass-of-calorimeter-water basis
10.3.3 Constant total-calorimeter-mass basis
10.3.4 ε as a function of the observed temperature rise
10.4 Expression of results
10.5 Calculation to other bases
11 Performance characteristics
11.1 Repeatability limit
11.2 Reproducibility limit
12 Calculation of net calorific value at constant pressure
12.1 General
12.2 Calculations
13 Test report
Annex A (normative) Adiabatic bomb calorimeters
Annex B (normative) Isoperibol and static-jacket bomb calorimeters
Annex C (normative) Automated bomb calorimeters
Annex D (informative) Checklists for the design and procedures of combustion experiments
Annex E (informative) Examples to illustrate the main calculations used in this document when an automated bomb calorimeter is used for determinations
Annex F (informative) List of symbols used in this document
Annex G (informative) Default values of most used solid biofuels for the calculations of calorific values
Annex H (informative) Flow chart for a routine calorific value determination
Bibliography
Index