Abstract: A heat exchanger device provides refrigeration in refrigerated vehicles operated by liquefied natural gas (LNG) which must first be regasified. The great temperature difference between heat-discharging cooling chamber air and heat-absorbing LNG evaporating at up to ?161° C. conducts the heat flow via an introduced intermediate medium circulating in a closed circuit to avert the risk of combustible natural gas leaking. The intermediate medium is non-combustible, environmentally-benign liquid heat exchange media having low viscosity. The liquid heat exchange media operating temperature is kept above ?85° C. using an additional thermal resistance in the heat exchanger which evaporates the LNG, so that the heat flow flows with sufficient temperature drop. A thin protective dry gas layer formed using sheathing tubes enclosing a tubular heat exchanger's tubes coaxially serves as this thermal resistance. Possibly escaping natural gas is determined by monitoring pressure in the layer, and the LNG supply interrupted.