Two $3$ cm$-$diameter thin$-$walled tubes run parallel, with their centers $5$ cm apart. Through one tube flows hot combustion gases at $800$ K$,$ while through the other flows water at $300$ K$.$ If both tubes have an emittance of $0\mathrm{.}8,$ calculate the net radiant energy absorbed by the water per meter length of tube. The surroundings are also at $300$ K$.$ Assume that both inside convective heat transfer coefficients are large.