An investigation on convective regasification heat transfer performance of supercritical methane inside horizontal heated circular tubes

The regasification technology in natural gas applications mostly involves supercritical methane (sCH4) heat transfer inside horizontal heated circular tubes. Precise evaluation of heat transfer behaviors and wall temperature is valuable for optimal design of advanced regasification equipment such as submerged combustion vaporizer (SCV) and intermediate fluid vaporizer (IFV). In this paper, the convective regasification heat transfer performance of sCH4 is investigated. Different heat transfer modes about normal heat transfer (NHT) and heat transfer deterioration (HTD) are observed. The mechanism of bimodal phenomenon is revealed through dividing five zones. Moreover, the transition law between NHT and HTD is deeply analyzed by holding the pseudo-boiling concept. Results show that there exist the multiple wall temperature peaks when HTD occurs. Two peaks mainly result from buoyancy effect near the wall region and shear stress in the mainstream region. Moreover, HTD is relevant to the rapid growth and large temperature gradient of gas-like fluid. The critical supercritical boiling number yielding for sCH4 is 8.415 × 10−4∼8.789 × 10−4. Finally, a new criterion concerning with critical heat flux is proposed to judge the occurrence of HTD. The present work lays a new way to understand the sCH4 regasification mechanism and provides reference for efficient operation of SCV and IFV.