NOVELTY - The geothermal heat exchanger includes heat exchange mechanism (H.E), subterranean water tube well (10), casing (20), suction pipe (30), circulating pipe (40), heat collection tank (50), pipe vacuum chamber (60), circulating pipe vacuum chamber (70), taper-shaped head (80) and pressurized clamp (90). The heat exchange mechanism is located outside the subterranean water tube well to function as a cooler to cool the subterranean water circulating in the subterranean water tube well during summer season, or as heater to heat the subterranean water during winter season.    USE - Geothermal heat exchanger used in exchanging terrestrial heat using subterranean water.    ADVANTAGE - Minimizes loss in geothermal heat by minimizing heat exchange between the subterranean water injected to the tube well and the subterranean water pumped to the ground.    DETAILED DESCRIPTION - The subterranean water stays at the bottom portion of the suction pipe which is arranged in the heat collection tank filled with heat exchange medium. The pipe vacuum chamber is installed at the bottom and top end portions of the suction pipe to minimize the heat exchange between the subterranean water and the surrounding of the suction pipe. The taper-shaped head is connected to the suction pipe and circulating pipe, and supported in the casing. The circulating pipe vacuum chamber surrounds the suction pipe, and is connected to the circulating pipe to ensure that pressure inside the circulating pipe does not rise. The pressurized clamp is connected to the circulating pipe vacuum chamber.    DESCRIPTION OF DRAWING(S) - The drawing shows the cross-sectional view of the heat exchanger used in exchanging terrestrial heat using subterranean water.    Subterranean water tube well (10)    Casing (20)    Suction pipe (30)    Circulating pipe (40)    Heat collection tank (50)    Pipe vacuum chamber (60)    Circulating pipe vacuum chamber (70)    Taper-shaped head (80)    Pressurized clamp (90)    Heat exchange mechanism (H.E)