... ,tight connection between fins and copper pipe to increase heat exchange efficiency.4.bright type copper tube thickness:0.35mm, ... design, Power conservation by 25%.7.cold-rolled steel plate for shell,phosphating static spraying technique,pleasing shape,rustproof.8 ... design, Power conservation by 25%.7.cold-rolled steel plate for shell,phosphating static spraying technique,pleasing shape,rustproof.8 ...