# Condensation Flow of Refrigerants Inside Mini and Microchannels: A Review
## 3 Condensation Flow of Refrigerants Inside Mini/Micro-Channels
### Numerical Studies Focused on Mini/Microchannel Condensation of Refrigerants
\begin{table}
\begin{tabular}{l l l l l} \hline \hline
**Researcher** & **Working Fluid** & **Geometry** & **Experimental Conditions** & **Purpose of Study** \\ \hline \multirow{2}{*}{[PERSON] [29]} & \multirow{2}{*}{R134a} & Round, square, and & \(D_{h}=\) 1–5 mm & Flow visualisations, \\  & & rectangular & \(G=\) 150–750 kg/m\({}^{2}\)s & heat transfer and \\  & & & & \(G=\) 150–750 kg/m\({}^{2}\)s & Pressure drop \\ \multirow{2}{*}{[PERSON] et al. [51]} & \multirow{2}{*}{n-pentane} & \multirow{2}{*}{a smooth tube} & \(D_{h}=\) 0.56 mm & Heat transfer analysis \\  & & & \(G=\) 3.4 and 13.8 kg/m\({}^{2}\)s & and flow visualisations \\ \multirow{2}{*}{[PERSON] et al. [52]} & \multirow{2}{*}{n-pentane} & \multirow{2}{*}{three smooth tubes} & \(D_{h}=\) 0.56 & Flow visualisations \\  & & & \(10\), 1.1, and 0.56 mm & \\  & & & \(D_{h}=\) 1.088 and 1.289 mm & Heat transfer \\ \multirow{2}{*}{[PERSON] et al. [53]} & \multirow{2}{*}{R22, R410A, and R407C} & two single-round & 0.56 mm & coefficients and \\  & & microchannels & \(G=\) 300–600 kg/m\({}^{2}\)s & two-phase pressure \\  & & & \(T_{sat}=\) 30–50 \({}^{\circ}\)C & drop \\  & & & \(x=\) 0.1–0.9 & Flow patterns and heat \\ \multirow{2}{*}{[PERSON] [54]} & \multirow{2}{*}{n-pentane} & \multirow{2}{*}{borosilicate square} & \(G=\) 3 and 15 kg/m\({}^{2}\)s & Flow patterns and heat \\  & & microchannel & \(T_{sat}=\) 36.06 \({}^{\circ}\)C & transfer characteristics \\  & & & \(D_{h}=\) 1.152 mm (circular) & \\  & & & \(D_{h}=\) 0.952 and 1.304 mm & \\ \multirow{2}{*}{[PERSON] et al. [55]} & \multirow{2}{*}{R32, R152a, and R22} & Circular and two & (square) & Heat transfer \\  & & square channels & \(G=\) 200–800 kg/m\({}^{2}\)s & characteristics \\  & & & \(T_{sat}=\) 30–50 \({}^{\circ}\)C & \\  & & & \(x=\) 0.1–0.9 & \\  & & & \(D_{h}=\) 1.152 mm (circular) & \\  & & & \(D_{h}=\) 0.952 and 1.304 mm & \\ \multirow{2}{*}{[PERSON] et al. [56]} & \multirow{2}{*}{R32, R152a, and R22} & Circular and two & (square) & Pressure drop \\  & & & \(T_{sat}=\) 30–50 \({}^{\circ}\)C & \\  & & & \(x=\) 0.1–0.9 & \\  & & & \(D_{h}=\) 1.085 mm (circular) & \\  & & & \(D_{h}=\) 0.952 mm & Heat transfer and \\ \multirow{2}{*}{[PERSON] et al. [57]} & \multirow{2}{*}{R1234 ze(E), and R22} & horizontal & \(G=\) 200–800 kg/m\({}^{2}\)s & pressure drop \\  & & microchannels & \(T_{sat}=\) 30–50 \({}^{\circ}\)C & \\  & & & \(x=\) 0.1–0.9 & \\ \multirow{2}{*}{[PERSON] et al. [58]} & \multirow{2}{*}{HFE-7100} & rectangular & \multirow{2}{*}{\(D_{h}=\) 0.57 mm} & Heat transfer \\  & & multi-microchannels & & coefficients and flow \\  & & & & visualisation \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Overview of recent experiments investigating the condensation of refrigerants in mini- and microchannels. ameter, considering both high (G = 800 kg/m\({}^{2}\)s) and low (G = 100 kg/m\({}^{2}\)s) mass fluxes. Their study incorporated the influences of interfacial shear stress, gravity, and surface tension on horizontal tube orientation. Subsequently, they extended their simulations to vertical downflow under normal gravity conditions and also performed simulations to assess non-gravity effects. Similarly, in their work, [PERSON] and [PERSON] [61] developed a numerical model to simulate laminar liquid film condensation in a horizontal circular minichannel with a 1 mm internal diameter. Utilising the volume of fluid (VOF) method, they conducted three-dimensional simulations of R134a fluid film condensation within the minichannel, exploring the impact of surface tension by comparing simulations with and without its consideration under their specified conditions. [PERSON] et al. [62] introduced a numerical model based on the VOF method to simulate fluid flow and heat transfer during condensation within a single microchannel.