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MHA Research Heater

"Substantially Similar" Study

January 15 - February 5, 2018

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The purpose of this study was to provide data to aid regulators in developing rules for allowing "families" of
manufactured heaters to be certified by testing only a subset of the complete model line.

The idea is that if the firebox is not modified between models, some leeway should be allowed in the configuration
of the heat exchangers.

For this series, we did 3 sets of 4 runs:

- 4 baseline runs. These verified prior runs to establish repeatability (coefficient of variation)
            data for the PM (particulate) emission value.
- 4 test runs as above, with the chimney modified to be closer to EPA laboratory testing specifications.
- 4 test runs with a substantial modification to the heat exchanger.

Heater firebox viewed from  instrumentation room side.

Firebox is connected to heat exchanger via insulated chimney pipe.
Heat exchanger exits into heated bench.
Heated bench is connected to chimney.

Cross section through firebox, insulated connecting pipe,
and heat exchanger. Gases exit at bottom right into heated
bench .

View from above.

Reconfigured heat exchanger.
Instead of 3 parallel downdraft channels, the channels are
connected in series.

Summary of test results.
        Temperatures are in degrees F.

PM emission factor (g/kg)
Uncertainty shown is from a previous repeatability study..

Note the relationship between firebox starting temperature and PM..
The highest PM number was an "Other" (ie., not part of the test series) run with a cold heater, cold fuel
and only a half load. (This was the curing fire after the heat exchanger modification).

Update: February 20, 2018:

Three additional test runs were performed with a change in fuel from dry oak to wet maple.
The maple was approx. 30% - 32% moisture (wet basis).
In the testing data (see below), they are runs MHA-1821, MHA-1822 and MHA-1823.
If we add the data to the graph, above, we get the following:

Go to Testing Data

Check out other current research at Lopez Labs

This page was updated on February 20, 2018
This page was created on  February 6, 2018