Methods of using component mass balance to evaluate manhole events

A method of estimating a size of a manhole event occurring in a selected manhole vault within a network of manhole vaults that are interconnected by connections, the method comprising:

• obtaining, by a system controller, an exhaust temperature, an exhaust mass, and an exhaust heat capacity for an exhaust flow, the exhaust flow exiting the selected manhole vault;
• obtaining, by the system controller, a fresh air temperature, a fresh air mass, and a fresh air heat capacity for a fresh air flow, the fresh air flow entering the selected manhole vault from an external atmosphere;
• determining, by the system controller, an event start time;
• obtaining, by the system controller, an anticipated base energy based on past base energy values, the event start time, and a current time;
• determining, by the system controller, an actual base energy at the current time based on the exhaust temperature, the exhaust mass, the exhaust heat capacity, the fresh air temperature, the fresh air mass, and the fresh air heat capacity;
• calculating, by the system controller, a difference between the actual base energy and the anticipated base energy at the current time;
• estimating, by the system controller, the size of the manhole event based on said difference;
• and
• performing, by the system controller, an action based at least in part on the size of the manhole event, the action including at least one of notifying one or more users or altering a turnover rate of atmospheric turnover in the selected manhole vault.