spraying pressures (P). It can be seen that the shapes of these curves are similar, the heat transfer coefficient increases first and then decreases as the continuous decreasing of the surface temper- ature, and the peak of the heat transfer coefficient appears in the temperature range of 100–150 oC. In the temperature range of
300–470 oC, very small differences exist among the heat transfer coefficients with different flux densities or spraying pressures. But in the range of 100–300 oC, the differences appear clearly.
Fig. 5 shows the relation curves of the maximum heat transfer coefficient (hmax) and the spraying pressure (P) with different flux densities (qs). With a same flux density, the increasing trend of the heat transfer coefficient is reduced obviously when the spraying pressure increases to a certain degree (200 kPa), except for a very large flux density (130 L m-2 s-1). The relation curves of the maximum heat transfer coefficient and the flux density with different spraying pressures are shown in Fig. 6. When the spraying pressure keeps not very high (such as 10 kPa and 50 kPa), the maximum heat transfer coefficient has a peak value. But for the case of higher pressure, hmax increases monotonously as the increasing qs, or it could be speculated that the peak value exists at a higher flux density.