GB2059567A

GB2059567A - Direct heat exchanger between two gases

Info

Publication number: GB2059567A
Application number: GB8023966A
Authority: GB
Original assignee: GAVIOLI G
Current assignee: GAVIOLI G
Priority date: 1979-07-27
Filing date: 1980-07-22
Publication date: 1981-04-23
Also published as: FR2462678B3; FR2462678A3; DE8019551U1; IT7904902V0

Abstract

In apparatus for heat exchange between two gases A, B, the gases are caused to pass respectively and in counterflow relation through alternate ones of parallel ducts formed by shaping a metal sheet 2. In the ducts there are fins (formed e.g. of metal sheets 4) connected to the sheet 2 and, for each gas, a single inlet conduit and a single outlet conduit are provided, partitioned from the respective outlet and inlet conduits for the other gas. <IMAGE>

Description

SPECIFICATION Direct heat exchanger between two gases This invention relates to a direct heat exchanger for exchanging heat between two gases which are flowing in counterflow relationship with each other.

In current heat exchangers, the direct exchange of heat between two gases occurs within the socalled crossflow exchangers.

In such exchangers, the two flows of gas move perpendicularly to each other, thus producing, as is well known, an average temperature differential between the two fluids which is much smaller than the one to be achieved in a counterflow exchanger. The reason why direct heat exchangers are designed to operate with cross-flows is that it is practically impossible to provide for the separation of the two flows to occur on the same face of the exchanger owing to the short height of the conduits.

The height of the conduits wherethrough the gas is flown, must be kept short both to increase the exchange surface area per unit of volume, and to improve the conditions of heat exchange between the fluid and the swept surface.

This invention sets out to obviate the problems affecting conventional gas heat exchangers, and in particular to increase the effective exchange surface area per unit volume and provide a counter-flow heat exchange between the two fluids.

Within the general aim, it is further possible to arrange that the heat exchanger according to this invention has a simple structure, comparatively easy to manufacture, reliable and effective in operation, as well as of comparatively low cost.

According to one aspect of the present invention, there is provided a direct heat exchanger for exchanging heat between two gases which are flowing in counterflow relationship with each other, characterised in that it comprises parallelepipedal conduits separated by metal sheets, wherein fins are formed connected to said metal sheets by virtue of which the two gases are caused, at the central portion of the exchanger, to follow alternately in counterflow relationship said conduits, in that for each gas a single inlet conduit and a single outlet conduit are provided in the exchanger, partitioned from the respective outlet and inlet conduits for the other gas by a metal sheet perpendicular to the metal sheets forming the conduits of said central portion, this being achieved by redirecting said conduits wherethrough a first gas flown to the side wherefrom said first gas is admitted to (or discharged from) the exchanger, thus leaving unobstructed for the other gas a corresponding passageway cross-section, the conduits for the second gas being deflected towards the opposite side.

Further features will be more clearly understood from the following description of a preferred but not limitative embodiment of a heat exchanger according to the invention, illustrated by way of example only in the accompanying drawing, where: Figure 1 is a sectional view of the central portion of the heat exchanger according to the invention, taken perpendicularly to the gas flows; Figure 2 is a sectional view of said heat exchanger, taken parallel to the metal sheets which provide for the separation of the two gases at the central portion of the heat exchanger; and Figure 3 is an overall view of that same heat exchanger.

With reference to the drawing figures, there is generally indicated at 1 a heat exchanger according to this invention. The heat exchanger comprises a metal sheet 2 which, when bent, shaped and welded at the ends 3 as shown in Figures 1, 2 and 3, separates the two gases from each other and from the environment, and the metal sheets 4 which form, inside each parallelepipedal conduit (Figure 1 ) a crowded set of fins increasing, by many times, the amount of heat exchanged per unit volume of the heat exchanger.

The metal sheets 4 are connected to the metal sheet 2 such as to create a good thermal contact; for example, by means of an aluminium sheet riveting or a dip zinc bath for iron sheets. In particular in Figure 2, there is shown how the gas A flows into and out of the exchanger following the path indicated by the arrows A, which have been dotted where the path A is covered by the metal sheet 2 which separates the two gases. The arrows B designate the path of the gas B. Thus, at the central portion of the heat exchanger where the exchange surface area is at a maximum, a counterflow motion of the two gases is achieved, thereby the objects specified in the preamble are achieved.

The invention as described is susceptible to many modifications and variations, all of which fall within the scope of this inventive concept.

Moreover, all of the details may be replaced with other technically equivalent elements.

In practicising the invention, the materials used as well as the shape and dimensions may be any ones to suit individual requirements, without departing from the true scope of the appended

claims.

CLAIMS 1. A direct heat exchanger for exchanging heat between two gases which are flowing in counterflow relationship with each other characterized in that it comprises parallelepipedal conduits separated by metal sheets, wherein fins are formed connected to said metal sheets by virtue of which the two gases are caused, at the central portion of the exchanger, to follow alternately in counterflow relationship said conduits, in that for each gas a single inlet conduit and a single outlet conduit are provided in the exchanger, partitioned from the respective outlet and inlet conduits for the other gas by a metal sheet perpendicular to the metal sheets forming the conduits of said central portion, this being achieved by redirecting said conduits

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Direct heat exchanger between two gases This invention relates to a direct heat exchanger for exchanging heat between two gases which are flowing in counterflow relationship with each other. In current heat exchangers, the direct exchange of heat between two gases occurs within the socalled crossflow exchangers. In such exchangers, the two flows of gas move perpendicularly to each other, thus producing, as is well known, an average temperature differential between the two fluids which is much smaller than the one to be achieved in a counterflow exchanger. The reason why direct heat exchangers are designed to operate with cross-flows is that it is practically impossible to provide for the separation of the two flows to occur on the same face of the exchanger owing to the short height of the conduits. The height of the conduits wherethrough the gas is flown, must be kept short both to increase the exchange surface area per unit of volume, and to improve the conditions of heat exchange between the fluid and the swept surface. This invention sets out to obviate the problems affecting conventional gas heat exchangers, and in particular to increase the effective exchange surface area per unit volume and provide a counter-flow heat exchange between the two fluids. Within the general aim, it is further possible to arrange that the heat exchanger according to this invention has a simple structure, comparatively easy to manufacture, reliable and effective in operation, as well as of comparatively low cost. According to one aspect of the present invention, there is provided a direct heat exchanger for exchanging heat between two gases which are flowing in counterflow relationship with each other, characterised in that it comprises parallelepipedal conduits separated by metal sheets, wherein fins are formed connected to said metal sheets by virtue of which the two gases are caused, at the central portion of the exchanger, to follow alternately in counterflow relationship said conduits, in that for each gas a single inlet conduit and a single outlet conduit are provided in the exchanger, partitioned from the respective outlet and inlet conduits for the other gas by a metal sheet perpendicular to the metal sheets forming the conduits of said central portion, this being achieved by redirecting said conduits wherethrough a first gas flown to the side wherefrom said first gas is admitted to (or discharged from) the exchanger, thus leaving unobstructed for the other gas a corresponding passageway cross-section, the conduits for the second gas being deflected towards the opposite side. Further features will be more clearly understood from the following description of a preferred but not limitative embodiment of a heat exchanger according to the invention, illustrated by way of example only in the accompanying drawing, where: Figure 1 is a sectional view of the central portion of the heat exchanger according to the invention, taken perpendicularly to the gas flows; Figure 2 is a sectional view of said heat exchanger, taken parallel to the metal sheets which provide for the separation of the two gases at the central portion of the heat exchanger; and Figure 3 is an overall view of that same heat exchanger. With reference to the drawing figures, there is generally indicated at 1 a heat exchanger according to this invention. The heat exchanger comprises a metal sheet 2 which, when bent, shaped and welded at the ends 3 as shown in Figures 1, 2 and 3, separates the two gases from each other and from the environment, and the metal sheets 4 which form, inside each parallelepipedal conduit (Figure 1 ) a crowded set of fins increasing, by many times, the amount of heat exchanged per unit volume of the heat exchanger. The metal sheets 4 are connected to the metal sheet 2 such as to create a good thermal contact; for example, by means of an aluminium sheet riveting or a dip zinc bath for iron sheets. In particular in Figure 2, there is shown how the gas A flows into and out of the exchanger following the path indicated by the arrows A, which have been dotted where the path A is covered by the metal sheet 2 which separates the two gases. The arrows B designate the path of the gas B. Thus, at the central portion of the heat exchanger where the exchange surface area is at a maximum, a counterflow motion of the two gases is achieved, thereby the objects specified in the preamble are achieved. The invention as described is susceptible to many modifications and variations, all of which fall within the scope of this inventive concept. Moreover, all of the details may be replaced with other technically equivalent elements. In practicising the invention, the materials used as well as the shape and dimensions may be any ones to suit individual requirements, without departing from the true scope of the appended claims. CLAIMS

1. A direct heat exchanger for exchanging heat between two gases which are flowing in counterflow relationship with each other characterized in that it comprises parallelepipedal conduits separated by metal sheets, wherein fins are formed connected to said metal sheets by virtue of which the two gases are caused, at the central portion of the exchanger, to follow alternately in counterflow relationship said conduits, in that for each gas a single inlet conduit and a single outlet conduit are provided in the exchanger, partitioned from the respective outlet and inlet conduits for the other gas by a metal sheet perpendicular to the metal sheets forming the conduits of said central portion, this being achieved by redirecting said conduits wherethrough a first gas flows to the side wherefrom said first gas is admitted to (or discharged from) the exchanger, thus leaving unobstructed for the other gas a correspondinq passageway cross-section, the conduits for the second gas being deflected toward the opposite side.

2. A heat exchanger according to Claim 1, characterized in that the finning of each of said conduits at the central portion is accomplished by a single metal sheet bent such as to establish thermal contact alternately with the two major walls of the conduit at the areas of contact with said walls of the metal sheets forming the fins of the conduit of the two adjacent conduits wherethrough the other fluid flows.

3. A heat exchanger according to one or more of the preceding claims, and as herein substantially described and illustrated for the objects specified.