ABSTRACT
With the advantages of high efficiency in heat transfer and compactness in structure, helical coils are extensively used in engineering applications such as heat exchangers, steam generators and chemical reactors. For these reasons, heat transfer from fluids flowing in helical pipes has become a research subject. As fluid flows through a curved pipe, secondary flows occur in planes normal to the main flow by the action of centrifugal force [1], resulting in a high increase in friction factors and heat transfer coefficients compared with that in an equivalent straight pipe [2].
