This　paper　presents　critical　analysis　of　process　modeling　and　mechanisms　of　CO2　evaporation　inside　macro-　and　micro-channels.　First,　some　existing　experimental　results　of　CO2　evaporation　heat　transfer　in　macro-channels　and　micro-channels　are　compared　and　discussed.　Then,　the　comprehensive　two-phase　flow　pattern　map　of　Cheng　et　al.　for　CO2　evaporation　inside　channels　is　presented.　The　flow　pattern　map　has　widely　been　used　to　predict　flow　patterns　of　CO2　evaporation　processes　and　favorably　agrees　with　observed　CO2　two　phase　flow　patterns　in　various　channels.　Next,　the　Cheng　et　al.　generalized　CO2　evaporation　heat　transfer　model　based　on　flow　patterns　is　compared　to　the　experimental　data.　It　has　been　proved　that　the　heat　transfer　model　favorably　agrees　with　the　experimental　data　by　many　researchers　over　the　past　decade.　Simulation　results　of　evaporation　heat　transfer　in　both　macro-　and　micro-channels　using　the　model　are　also　presented.　Furthermore,　evaporation　heat　transfer　mechanisms　are　analyzed　from　the　flow　regime　variations　and　unstable　evaporation　heat　transfer　characteristics　in　both　macro-　and　micro-channels.　Finally,　applications　of　the　Cheng　et　al.　CO2　evaporation　heat　transfer　model　in　evaporator　design　for　various　thermal　systems　are　reviewed.　Future　research　needs　are　identified　according　to　this　comprehensive　analysis　and　review.