Domestic　heat　exchangers,　even　though　widely　used　in　industry,　are　not　adequate　for　studies　on　low-temperature　flue-gas　use　technologies.　Despite　spite　their　limitations,　very　few　theoretical　models　have　been　investigated　based　on　practical　applications.　Moreover,　most　of　the　existing　studies　on　heat　exchangers　have　focused　particularly　on　one-dimensional　and　two-dimensional　heat　transfer　models,　while　limited　studies　focus　on　three-dimensional　ones.　Therefore,　this　study　aims　at　investigating　the　thermal　performance　of　a　low-temperature　flue-gas　heat　recovery　unit　in　the　cold　regions.　Specifically,　this　study　was　conducted　in　the　context　of　Changchun　of　Jilin　Province,　China,　a　city　with　the　mean　ambient　temperature　of　-14　degrees　C　and　mean　diurnal　temperature　of　-10　degrees　C　during　winter.　Experimental　results　showed　that　the　thermal　efficiency　of　the　heat　exchanger　was　higher　than　60%.　Through　assessing　the　heat　exchange　coefficient　and　heat　exchange　efficiency　of　the　heat　exchanger,　it　is　found　that　the　thermal　efficiency　had　been　improved　up　to　0.77-0.83.　Furthermore,　the　ICEPAK　software　and　the　standard　k-epsilon　RNG　turbulence　model　were　used　to　carry　out　simulations.　The　velocity　and　outlet　temperature　of　fresh　airflow　and　polluted　airflow　were　simulated　through　setting　different　inlet　temperatures　of　fresh　air　and　polluted　air　inlet.　Numerical　results　further　indicated　that　the　flow　state　was　laminar　flow.　The　micro　heat　pipe　array　side　had　small　eddies　and　the　heat　transfer　was　significantly　improved　due　to　the　flow　of　air　along　the　surface　of　the　micro　heat　pipe.