The equation #2C_3H_7OH(g) + 9O_2(g) -> 6CO_2(g) + 8H_2O(g) is an example of what type of reaction?

$\text{A combustion reaction.......}$
${C}_{3} {H}_{7} O H \left(l\right) + \frac{9}{2} {O}_{2} \left(g\right) \rightarrow 3 C {O}_{2} \left(g\right) + 4 {H}_{2} O \left(l\right) + \Delta$
What does the $\Delta$ symbol represent in the products?