Flow boiling frictional pressure drop inside micro/mini-channels : A new general model and experimental investigation

• In this study, a novel general model for flow boiling frictional pressure drop inside micro/mini-channels was proposed based on theoretical analysis and experimental evaluation. Experiments were conducted to obtained flow boiling pressure drop of deionized water, HFE7100 and R134a in micro-channels under various experimental conditions. Then, a wide database from 33 previous literatures consists 3854 experimental data points covering 11 different working fluids, e.g., carbon dioxide, new electronic fluorinated solutions, refrigerants and deionized water, among others, and the operation conditions were as following: system temperature of −40–90 ℃, saturated pressure of 101–3970 kPa, hydraulic diameter of 0.1–2.6 mm, liquid subcooling of 5–75 K, mass flux of 50–3000 kg/(m2·s), heat flux of 0–4000 kW/m2, liquid-only Reynolds number of 40–12,000, vapor quality of 0–1, and reduced pressure of 0.0045–0.5380 in the database. Both the Reynolds numbers of vapor and liquid were calculated using the hydraulic diameter and vapor quality. The present data points were evaluated by 20 existing classical models (including the homogeneous and separated flow ones) for the flow boiling frictional pressure drop. However, the predictions of these models for the present data points had low accuracy, especially for the subcooled points at low vapor quality. Therefore, a more accurate prediction model was developed based on the present database by distinguishing the subcooled and saturated boiling. This novel prediction model can predict 75.4 % and 89.7 % of data points within ±30 % and ±50 % error bands, its mean absolute percent error (MAPE) is 19.23 %, which shows good predictive ability. Besides, the reliability of the new model was also further verified with our experimental results.

Ämnesord

TEKNIK OCH TEKNOLOGIER  -- Maskinteknik -- Energiteknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Mechanical Engineering -- Energy Engineering (hsv//eng)

Nyckelord

Flow boiling

Frictional pressure drop

Micro/mini-channels

Prediction model

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art (ämneskategori)

ref (ämneskategori)