A heat exchanger for cooling heated gas using a liquid coolant includes a tubular housing with one or more intake apertures circumferentially spaced around a coolant distribution portion of the housing. A tube retention cap sealedly engages the front end of the tubular housing, and includes at least one gas tube orifice. An annular coolant chamber surrounds the coolant distribution portion, which distributes liquid coolant around the intake apertures and directs coolant into the cavity and within the tubular housing. Positioned within the tubular housing is at least one elongated gas tube, which is sealedly engaged with the tube orifice. Liquid coolant flowing in, through a coolant inlet, is directed around the annular coolant chamber and distributed into the cavity of the tubular housing, immersing the elongated gas tube and facilitating heat exchange from the heated gas flowing through the elongated gas tubes immersed within the liquid coolant.