Under contract with NORESCO, Boulder, CO, the CONTAM model developed and supported by the National Institute of Standards and Technology (NIST) will be used to model NO₂ concentration development from measurements of NO₂emissions from residential cooktops and ovens compiled in late 2019 by CSA Group and reported in previous BECS Codes and Standards “Friday Updates.” At the kickoff meeting Friday, the CSA Group data was reviewed with the NORESCO team to identify uncertainties in the source rates and methods for translating the data into unit inputs for CONTAM concentration calculations.  Under the Phase 1 simulations, a two-chamber model (kitchen and adjacent space) will be simulated with some parametric cases defined to characterize differences in kitchen volume and development of room concentrations as the basis for exposure characterizations.  While Phase 1 will be limited to NO₂ concentration development, a “Phase 2” CONTAM modeling program will address the five emission classes (CO, NO₂, particulate matter in two size ranges, formaldehyde, and acrolein) that will be measured in the joint AHAM, AGA, CGA testing program.  CONTAM model definition will be completed next week along with NO₂ emission conversions from volumetric data reported by CSA Group to mass emission rates that can be used directly as CONTAM model input.  As part of the model definition, documented and validated examples of two-chamber CONTAM modeling designs for other indoor air quality (IAQ) studies will be used.  Phase 1 modeling is expected to be completed in early 2021.  As with the collection of NO₂source emission rates, the modeling will be the first studies by the natural gas industry to estimate potential exposures of residential occupants to NO₂ from use of household cooking appliances.

 

This week at the ANS Z21/83 TC meeting held virtually, the results of the blended methane/hydrogen supply gas tests on various gas appliances performed by Appliance Engineering, Inc. (AEI), Twinsburg, OH were presented for the TC’s consideration for possible future standards action and additional testing.  As the originator of the testing program, which included sponsorship from AGA, AHRI, and CSA Group and overseen by an Advisory Committee of AHRI members and the sponsors, AGA sought to develop “exploratory” test data to help identify potential operability issues for domestic gas appliances when operated on methane/hydrogen mixtures of 5% and 15% hydrogen.  Results of the AEI will be fully documented in a public report currently being developed by CSA Group.  As reported in earlier BECS Codes and Standards “Friday Updates,” the testing program covered five appliance categories with broad differences in combustion and heat recovery technologies within each appliance category as well as potential leakage from appliances and gas supply piping.  Definitive findings on appliance operability and leakage on the hydrogen blends were not made in the testing project due to emphasis of the scope to exploratory testing to identify more detailed technical issues.  However, key findings suggested by the testing were documented for changes in appliance output conforming to theoretical descriptions, appliance ignition, and stability of steady state operation.  Working with the other sponsors, AGA will seek follow up with the TC regarding further implications of the testing results once members have had an opportunity to review the testing in more detail.  One near-term initiative coming out of the testing and objectives voiced by gas suppliers advocating hydrogen blending of natural gas is to develop proposed revisions to Z21 standards test gases to include natural gas/hydrogen blends of up to 15% to be used in design certification for safety.

 

 

[This is a weekly feature of the “Friday Update” covering state code calendar activities as presented by the online utility “Fiscal Note,” which is sponsored by APGA and AGA Code and Standards.]