Spiral wound heat exchangers are often used for LNG（liquefied naturalgas）vaporization on ships because of the advantages of their high efficiency

compactness

and high mechanical strength. The structure of heat exchangers should be designed properly to prevent the problem of freezing blockage. This paper proposes a design to prevent the freezing blockage when meeting the process requirements. Firstly

the basic idea of designing an anti-freeze heat exchanger is to figure out the key parameters of heat exchangers under the condition that the temperature of water in the tubes is higher than freezing point and the outlet temperature on the tube side is evenly distributed. A 3D-distributed-parameter model is adopted to verify the heat transfer

pressure drop

and anti-freeze performance of the heat exchanger. Finally

the structure readjustment is developed. The proposed design method is used on a practical LNG spiral wound heat exchanger. The designed heat exchanger meets the requirements for preventing freezing blockage

and satisfies the requirements of heat transfer and pressure drop. The design results show that the minimum wall temperature on tube side is 7.32℃

whereas the even outlet temperature on the tube sideis 31.42℃

which achieves the purpose of preventing freezing blockage.