A heat radiation device includes a heat source, a meta-material structure layer arranged on a front surface side of the heat source and configured to radiate radiant energy in a specific wavelength range by converting heat energy inputted from the heat source into the radiant energy in the specific wavelength range, and a rear-surface metal layer arranged on a rear surface side of the heat source. An average emissivity of the rear-surface metal layer is smaller than an average emissivity of the meta-material structure layer.

A heating furnace includes a bolt inserted through an insertion hole in a part of a heater and further inserted into a hole on a tip surface of an electrode rod. A first washer is between a bearing surface of the bolt and one face of the heater. A second washer is between another face of the heater and the tip surface. The relation of: |L.sub.0.Math..sub.0(T.sub.H.Math..sub.H+T.sub.B.Math..sub.B+T.sub.E.Math..sub.E)|.Math.T0.15(T.sub.B+T.sub.E) is satisfied, where L.sub.0 is an interval between the bearing surface and the tip surface, .sub.0 is a linear expansion coefficient (LEC) of the bolt, T.sub.H, T.sub.B and T.sub.E are thicknesses of the part, first and second washers and .sub.H, .sub.B and .sub.E are their LECs, respectively, and T is a temperature increment quantity of a part where the heater and the electrode rod are fastened by the bolt.

A heating furnace includes a bolt inserted through an insertion hole in a part of a heater and further inserted into a hole on a tip surface of an electrode rod. A first washer is between a bearing surface of the bolt and one face of the heater. A second washer is between another face of the heater and the tip surface. The relation of: |L.sub.0.Math..sub.0(T.sub.H.Math..sub.H+T.sub.B.Math..sub.B+T.sub.E.Math..sub.E)|.Math.T0.15(T.sub.B+T.sub.E) is satisfied, where L.sub.0 is an interval between the bearing surface and the tip surface, .sub.0 is a linear expansion coefficient (LEC) of the bolt, T.sub.H, T.sub.B and T.sub.E are thicknesses of the part, first and second washers and .sub.H, .sub.B and .sub.E are their LECs, respectively, and T is a temperature increment quantity of a part where the heater and the electrode rod are fastened by the bolt.

A furnace heater includes a first conductive lead, a second conductive lead spaced apart from the first conductive lead by a first distance, and a first helical resistive heater element connected to the first conductive lead. The furnace heater also includes a second helical resistive heater element connected to the second conductive lead and to the first helical resistive heater element, the second helical resistive heater element spaced apart from the first helical resistive heater by a second distance, wherein the first distance is at least twice the second distance.

A furnace heater includes a first conductive lead, a second conductive lead spaced apart from the first conductive lead by a first distance, and a first helical resistive heater element connected to the first conductive lead. The furnace heater also includes a second helical resistive heater element connected to the second conductive lead and to the first helical resistive heater element, the second helical resistive heater element spaced apart from the first helical resistive heater by a second distance, wherein the first distance is at least twice the second distance.

In a heater unit for a carburizing furnace that carburizes a workpiece, a heater that heats a furnace atmosphere; and a heater supporting member that reflects radiant heat of the heater are provided, in which a heat generation part of the heater is attached to the heater supporting member, and a heat generation body composing the heat generation part is formed in a bellows shape.

In a heater unit for a carburizing furnace that carburizes a workpiece, a heater that heats a furnace atmosphere; and a heater supporting member that reflects radiant heat of the heater are provided, in which a heat generation part of the heater is attached to the heater supporting member, and a heat generation body composing the heat generation part is formed in a bellows shape.

The present invention relates to a process of making power-saving electric stoves, particularly having a large size and outer shapes similar to the conformations of traditional Tyrolean heaters or stoves, while having a very light weight and being easily movable to multiple locations of a house. The main characteristic of the present invention is that it includes making a hollow stove body, particularly having a large size, from expanded polystyrene or a similar thermoplastic polymer, with the application of an electric resistor, particularly a constant-power, and hence low-power consuming heating cable arranged around its outer surface in one or more coil loops with the interposition of a layer of adhesive material with at least one thread formed therein for supporting the resistor, with contiguous insulating grooves, and with later application of a final coating layer, made e.g. of tire-resistant cement mortar, whose outer surface may be provided with decorative designs or finishes and ornaments made of wood or other materials, which designs and ornaments may be similar to those formed on the outer surfaces of traditional Tyrolean stoves, whereas the basement of the hollow body is preferably supported by a smooth metal plate, allowing displacement thereof to any location of the house, proximate to a power outlet.

Provided is a molten metal holding furnace with heat dissipation and insulating properties. An insertion hole 20 of a molten metal holding furnace 10 has an inside cylindrical portion (tapered surface) 21 and an outside cylindrical portion 22 (cylindrical surface). A heating tube 30 has a distal cylindrical portion 35 corresponding to the inside cylindrical portion 21 and a proximal cylindrical portion 36 corresponding to the outside cylindrical portion 22. The heating tube 30 is inserted and positioned in the insertion hole with the distal cylindrical portion 35 positioned at the inner cylindrical portion 21 and the proximal cylindrical portion 36 positioned at the outside cylindrical portion 22. A filling material 60 is filled between the heating tube 30 and the insertion hole 20.

Provided is a molten metal holding furnace with heat dissipation and insulating properties. An insertion hole 20 of a molten metal holding furnace 10 has an inside cylindrical portion (tapered surface) 21 and an outside cylindrical portion 22 (cylindrical surface). A heating tube 30 has a distal cylindrical portion 35 corresponding to the inside cylindrical portion 21 and a proximal cylindrical portion 36 corresponding to the outside cylindrical portion 22. The heating tube 30 is inserted and positioned in the insertion hole with the distal cylindrical portion 35 positioned at the inner cylindrical portion 21 and the proximal cylindrical portion 36 positioned at the outside cylindrical portion 22. A filling material 60 is filled between the heating tube 30 and the insertion hole 20.