Heater and water dispenser

The invention relates to the technical field of water dispensers, and provides a heater and a water dispenser, the heater comprises a heating pipe and a jet flow assembly, the jet flow assembly is provided with a jet flow cavity, a water inlet and a plurality of jet flow holes, the water inlet and the jet flow holes are communicated with the jet flow cavity, a water passing gap is formed between the outer wall face of the jet flow cavity and the inner wall face of the heating pipe, and the water inlet faces a liquid inlet port; wherein the ratio of the total area of all the jet flow holes to the area of the inner wall of each jet flow cavity ranges from 0.94% to 78.35%, and the distance between the two jet flow cavities in the length direction of the heating pipe ranges from 2 mm to 12 mm. Liquid flowing out of the liquid flow through the jet flow holes directly exchanges heat with the heating pipe, the heat exchange efficiency of the liquid flow is improved, meanwhile, by limiting the hole proportion of the jet flow holes in the jet flow cavities and limiting the distance between the adjacent jet flow cavities, the liquid flow can be efficiently heated, and the heat exchange efficiency is improved. And meanwhile, the heat exchange coefficient, the Nusselt number and the pressure drop of the heater can be in a better range, so that the pressure drop of the jet flow cavity and the heat exchange efficiency between the liquid flow and the heating wall surface are balanced.