Method for operating an automated two-burner biomass cookstove

Abstract

A two-blower automated biomass cookstove with sensors that dynamically adjusts air independent air flows and optimizes for the fresh fuel phase, but also manages air through a transitional phase, and then a char phase. The cookstove comprises a housing; a combustion assembly mounted within the housing, dual air flow passageways disposed at least partially within the housing for communicating air flow from outside the housing to a combustion cup, and a control system for automatically and dynamically adjusting relative air flow between the primary and secondary air flow passageways to optimize performance.

We claim: 
     
         1 . A method for operating an automated two-blower cooking stove, the automated two-blower cooking stove having a combustion chamber, the housing having a primary air flow passage, a secondary air flow passage, a primary blower and a secondary blower, the combustion chamber having primary air holes, secondary air holes, a combustion cup base, and a flame well, the secondary air holes disposed above the primary air holes, the primary blower in communication with the primary air holes, the secondary blower in communication with the secondary air holes, the combustion cup base adjacent the primary air holes, the flame well adjacent the secondary air holes, the method comprising:
 detecting that rate of change of the temperature of the combustion cup base has exceeded a reference change rate, and if so:
 adjusting the speed of the secondary blower to increase the amount of air blowing into the secondary air flow passage to optimize combustion at the flame well. 
   
     
     
         2 . The method for operating an automated two-blower cooking stove of  claim 1  wherein adjusting the speed of the secondary blower comprises:
 increasing the speed of the primary blower in a plurality of steps by a first set of pre-established increments over a transition time, 
 increasing the speed of the secondary blower serially after each of said plurality of steps by a second set of pre-established increments over said transition time, and 
 detecting that the temperature of the combustion cup base has reached a pre-established “CHARFLIP” temperature or that said transition time has expired, and if so:
 terminating the increases of speeds of the primary and secondary blowers. 
 
 
     
     
         3 . The method for operating an automated two-blower cooking stove of  claim 1  further comprising:
 detecting that the temperature of the flame well has fallen below a pre-established shutdown temperature, and if so:
 turning off the primary and secondary blowers. 
 
 
     
     
         4 . The method for operating an automated two-blower cooking stove of  claim 1  further comprising:
 detecting that the temperature of the flame well has fallen by a rate greater than a pre-established rate indicated in a configuration file, and if so:
 turning off the primary and secondary blowers. 
 
 
     
     
         5 . The method for operating an automated two-blower cooking stove of  claim 1  further comprising:
 determining if the current speeds of the primary and secondary blowers are at pre-established speeds indicated in a configuration file for a target flame level set by a potentiometer, and if so:
 increasing or decreasing the speeds of the primary and secondary blowers until said current speeds meet the speeds indicated by said target flame level. 
 
 
     
     
         6 . The method for operating an automated two-blower cooking stove of  claim 5  wherein if said current speeds are lower than the speeds indicated by said target flame level:
 increasing the speed of the secondary blower in a plurality of steps by a first set of pre-established increments, and 
 increasing the speed of the primary blower serially after each of said plurality of steps by a second set of pre-established increments. 
 
     
     
         7 . The method for operating an automated two-blower cooking stove of  claim 5  wherein if said current speeds are higher than the speeds indicated by said target flame level:
 decreasing the speed of the primary blower in a plurality of steps by a first set of pre-established increments, and 
 decreasing the speed of the secondary blower serially after each of said plurality of steps by a second set of pre-established increments. 
 
     
     
         8 . The method for operating an automated two-blower cooking stove of  claim 1  further comprising:
 determining that the temperature of the flame well is less by a pre-established increment than the temperature of the combustion cup base, and if so:
 setting the speeds of the primary and secondary air blowers at a pre-established level, and 
 
 determining after a pre-established time interval has elapsed that the temperature of the flame well is greater than a pre-established shutdown temperature, and if so:
 increasing the speeds of the primary and secondary blowers to speeds indicated in a configuration file for a target flame level set by a potentiometer. 
 
 
     
     
         9 . The method for operating an automated two-blower cooking stove of  claim 1  further comprising:
 determining that the temperature of the flame well is greater by a pre-established increment than the temperature of the combustion cup base, and if so:
 increasing the primary and secondary blowers to begin stepped increases of speed to speeds indicated in a configuration file. 
 
 
     
     
         10 . A method for operating an automated two-blower cooking stove, the automated two-blower cooking stove having a combustion chamber, the housing having a primary air flow passage, a secondary air flow passage, a primary blower and a secondary blower, the combustion chamber having primary air holes, secondary air holes, a combustion cup base, and a flame well, the secondary air holes disposed above the primary air holes, the primary blower in communication with the primary air holes, the secondary blower in communication with the secondary air holes, the combustion cup base adjacent the primary air holes, the flame well adjacent the secondary air holes, the method comprising:
 determining if the current speeds of the primary and secondary blowers are at pre-established speeds indicated in a configuration file for a target flame level set by a potentiometer, and if so:
 increasing or decreasing the speeds of the primary and secondary blowers until said current speeds meet the speeds indicated by said target flame level, and 
   detecting that rate of change of the temperature of the combustion cup base has exceeded a reference change rate, and if so:
 adjusting the speed of the secondary blower to increase the amount of air blowing into the secondary air flow passage to optimize combustion at the flame well, and 
   detecting that the temperature of the flame well has fallen below a pre-established shutdown temperature, and if so:
 turning off the primary and secondary blowers. 
   
     
     
         11 . A method for operating an automated two-blower cooking stove, the automated two-blower cooking stove having a combustion chamber, the housing having a primary air flow passage, a secondary air flow passage, a primary blower and a secondary blower, the combustion chamber having primary air holes, secondary air holes, a combustion cup base, and a flame well, the secondary air holes disposed above the primary air holes, the primary blower in communication with the primary air holes, the secondary blower in communication with the secondary air holes, the combustion cup base adjacent the primary air holes, the flame well adjacent the secondary air holes, the method comprising:
 determining that the temperature of the flame well is less by a pre-established increment than the temperature of the combustion cup base, and if so:
 setting the speeds of the primary and secondary air blowers at a pre-established level, 
   determining after a pre-established time interval has elapsed that the temperature of the flame well is greater than a pre-established shutdown temperature, and if so:
 increasing the speeds of the primary and secondary blowers to speeds indicated in a configuration file for a target flame level set by a potentiometer, and 
   detecting that rate of change of the temperature of the combustion cup base has exceeded a reference change rate, and if so:
 adjusting the speed of the secondary blower to increase the amount of air blowing into the secondary air flow passage to optimize combustion at the flame well, and 
   determining if the current speeds of the primary and secondary blowers are at pre-established speeds indicated in a configuration file for a target flame level set by a potentiometer, and if so:
 increasing or decreasing the speeds of the primary and secondary blowers until said current speeds meet the speeds indicated by said target flame level. 
   
     
     
         12 . The method for operating an automated two-blower cooking stove of  claim 11  further comprising:
 determining that the temperature of the flame well is greater by a pre-established increment than the temperature of the combustion cup base, and if so:
 increasing the primary and secondary blowers to begin stepped increases of speed to speeds indicated in a configuration file.