Compact inward-firing premix fuel combustion system, and fluid heating system and packaged burner system including the same

A combustion burner, comprising:

• a burner casing configured to receive a fuel-air mixture at a burner inlet and to provide hot combustion gas at a burner output;
• a combustion substrate disposed within the burner casing, the substrate having a shape comprising at flat surface, having a substrate porosity defined by a plurality of pores, the pores having a 3-dimensional structure having a predetermined thickness, and having a substrate inner surface and a substrate outer surface;
• the substrate configured to receive the fuel-air mixture at the outer surface of the substrate, the fuel-air mixture passing through the pores at a mixture flow rate from the substrate outer surface toward the substrate inner surface;
• the burner configured such that, in operation, the fuel-air mixture ignites in a reaction zone inside a combustion cavity near the plurality of pores to form a respective plurality of flamelets, each flamelet corresponding to one of the pores;
• and
• wherein the porosity is set such that a flame equilibrium ratio (ρ) causes the reaction zone, for 1<ρ<100, to be approximately stationary and inside the combustion cavity.

A combustion burner, comprising:

• a burner casing configured to receive a fuel-air mixture at a burner inlet and to provide hot combustion gas at a burner output;
• a combustion substrate disposed within the burner casing, the substrate having a shape that is substantially flat, having a substrate porosity defined by a plurality of pores, the pores having a 3D shape comprising a predetermined thickness, and having a substrate inner surface and a substrate outer surface;
• the substrate configured to receive the fuel-air mixture at the outer surface of the substrate, the fuel-air mixture passing through the pores at a mixture flow rate from the substrate outer surface toward the substrate inner surface;
• the burner configured such that, in operation, the fuel-air mixture ignites in a reaction zone inside a combustion cavity near the plurality of pores to form a respective plurality of flamelets, each flamelet corresponding to one of the pores, wherein the plurality of flamelets exhibits suspended flame combustion (SF combustion);
• and
• wherein the porosity is set such that a flame equilibrium ratio (ρ) causes the reaction zone, for 1<ρ<100, to be approximately stationary and inside the combustion cavity.