A HEAT ACCUMULATOR

Abstract: A heat accumulator in the shape of a heat exchanger of the regenerative type comprising a plurality of aluminum plates (11) disposed closely spaced so as to form channels therebetween for the inlet air and exhaust air, respectivelly. The plates (11) are disposed in a good heat conducting contact with closed tube loops (12), containing a liquid heat absorbing medium. The closed tube loops (12) are formed by U-shaped loops, the straight shanks (12A, 12B) of which are passed through the plates (11) and the shank ends of which are interconnected in pairs. The tube loops (12) are expanded into contact with the walls of the holes in the plates. The heat absorbing liquid mixture consists of water and glycol, in the proportions 70 percent by volume of water and 30 percent by volume of glycol.

Description: A heat accumulator. The present invention relates to a heat accumulator, an more precisely to a heat accumulator of the kind which is <r defined in the preamble of claim 1. 5 Heat recovering assemblies for houses, factories, hospitals and other premises have been proposed which are provided with one or more heat accumulators in the shape of bundles of closely spaced plates, e.g. of aluminum, between which there are formed channels for the air. The exhaust 10 air and inlet air may be passed alternating through the channels by intermittently changing the flow direction by means of suit-able valves. Thus, heat accumulators of this kind are so called regenerative heat exchangers. A basic ccminor- feature of the pior regenerative heat 15 exchangers is that they - for each given choice of material for the plates o the bundle - have been considered requir- ing a big plate mass in order that the required capacity should be obtained. Here, the word capacity is used to denote the ability to take up and store, and then to give 20 off the required quantity of heat energy. Due to the requirement for a big plate mass the prior art regenerative heat exchangers have become rather heavy and expensive in manufacture. The present invention has aimed at avoiding the the just 25 mentioned problems and to provide a regenerative heat exchanger which moreover has the advantage that it is easy to manufacture ar-.d is very rugged mechanically. To the just r.entioned end the heat accumulator according to the present invention has been designed so as is defined 30 in principle in the characterizing clause of claim 1. i The invention will be disclosed in more details below with reference to the accompanying drawing. Fig. 1 is a very simplified perspective view of one embodiment of a heat accumulator according to the invention; 35 Fig. 2 is and end view of a portion of the heat accumul¬ ator in fig. I. The heat accumulator 10 comprises a plurality of paral¬ lel closely spaced plates 11, e.g. of aluminum. The size of the plates may be e.g. 1000 x 1000 mm and they may have a thickness of only 0,25-0,30 mm. The spacing between the plates may be e.g. 3 mm. Through the plates 11 there extends a plurality of tubes 12, e.g. of copper. The tubes may have an outer diameter of e.g. 16 mm and a wall thickness of e.g. 0.5 mm. The tubes 12 may be straight tube pieces, but they may also constitute straight shanks 12A, 12B of tubes that have been bent into U-shape as shown in the drawing. In the example the shanks 12A,12B are interconnected by means of a connecting piece 12C in such a manner that a rather elongated, somewhat oval closed loop is formed. Also ether interconnections of the individual tubes to form closed systems are concievable. In the example the tubes 12 may be filled with a suit¬ able liquid mixture, such as a mixture of 70 percent by volume of water c.nd 30 percent by volume of ethylene glycol. Such a mixture is suitable with respect both to the price and the function, but depending on the particular require¬ ments in each case also other liquid mixtures or solutions may be suitable. The tubes 12 must be in good heat conducting contact with the plates 11. In practise this is obtained in that the plates 11 are provided with holes, if desired with a circumferenticn edge flange, which holes are slightly oversized in relεtion to the cuter diameter of the tubes, whereafter the plates are placed over the tubes 12, which are disposed in a fixture. Then a mandrel is pushed throug each one of the tubes so as to lastingly expand them into heat conducting contact with the walls of the holes in the plates or with the inner sides of the flanges, if such have been formed. Subsequent to the just disclosed mounting the plate bundles are provided with a surrounding frame 13, and with an outer lining in a suitable way, not shown. The following example serves to illustrate the advantag as to the price of the heat accumulator according to the invention. At cor air velocities and other parameters there is 3 used for a heat accumulator for an air flow of 10000 m /h about 400 kg of aluminum plate of 0,7 mm thickness, which with the specific heat C for Al of 0,226 kcal/K gives a heat accumulation capacity of 90,5 kcal/K. With all czher values ramaining unchanged but use of aluminum plates of a thickness of 0,25 mm, copper tubes of 5 an outer diameter of 16 mm and an inner diameter of 15 mm and C = 0,1 and a liquid mixture of 70 vol.- water and 30 vol.-% glycol with C=0,9 the values could be added as follows: 0,25 mm Al-plate: 123,8 kg x 0,226 28,0 kcal/K 10 Cu-tubes 84 kg x 0,1 8,4 kcal/K H-0 + glycol 60 kg x 0,9 54,0 kcal/K 267,8 kg 90,4 kcal/K It is essential that the weight of the bundle has been reduced cc. ..jrably and that the v/eight of the aluminum 15 plates could be reduced to less than a third, which is important with the present high price of aluminum. ; - -

Claims: Calims . .1. A heat accumulator in the shape of a heat exchanger of the regenerative type, comprising a plurality of plates (11), e.g. of aluminum, which are disposed closely spaced so as to form channels therebetween for a flow back and forth of inlet air and exhaust air, repectively, during an inter¬ mittent alternating of the flow direction, characterized in that the plates (11) are arranged in a good heat conducting contact with preferably closed tube loops (12) containing a liquid heat absorbing medium. 2. A heat, accumulator as claimed in claim 1, character ized in that the closed tube lcops (12) are constituted by U-shaped loops, the straight shanks (12A,12B) of which are passed through the plates and the shank ends of which are interconnecte in pairs. 3. A heat, accumulator as claimed in claim 1 or 2, characterized in that the closed tube loops (12) are formed by staight tube pieces the ends of which are interconnected in pairs. 4. A heat accumulator as claimed in one or more of claims 1-3, characterized in that the tube loops (12) are permanently expanded from inside and out into contact with the wall.. he holes. 5. A heat accumulator as claimed in one or more of claims 1-4, characterized in that the heat absorbing liquid mixture consists of water and glycol, e.g. in the proport¬ ions 70 percent by volume of water and 30 percent by volume of glycol. OMPI

Inventors: GRUENIGER EMIL, GRUENIGER, EMIL
Applicants: GRUENIGER EMIL, STENFORS ERIC, GRUENIGER, EMIL, STENFORS, ERIC
Application year: 1983
Main classification: F28D17
IPC codes: F28D17