Heat Exchanger

Abstract

The invention presents a MONOBLOC fin and plate heat exchanger design preventing internal leakages and intermixing of high-temperature and low-temperature flows, e.g. oil and fuel. This is achieved through a particular configuration of the heat exchanger, whereby its core assembly is completely or partially produced from a one-piece monolithic metallic block. Owing to that, all brazed seams, which in conventional fin and plate heat exchangers contact with both hot medium and cold medium flows, are fully abolished thereby excluding a source for imperfections usually developing in brazed joints and base metal in the process of pressure-temperature cyclic loading. Employing custom-made individual fins allows about two-fold increase in the strength of brazed joints in comparison with ordinary corrugated fins (due to doubling of the brazed surface). As a result, the suggested configuration allows the design of a high reliability compact heat transfer device for much higher operating pressures than what may be achieved in the conventional fin and plate heat exchanger. This invention may be used in different fields of modern technology, especially for aeronautical engine applications, where the challenge of ensuring reliability levels of one failure in millions of (fleet-cumulative) flight hours, and operating pressure levels of thousands of pounds per square inch, must be met.

1 . A compact plate and fin heat exchanger
 comprising a core assembly and, welded or attached thereon, two sets of inlet and outlet headers for low temperature and high temperature gas or liquid fluid flows;   and said core assembly incorporates a plurality of functional elements identified as low temperature and high temperature fins, parting sheets, end plates and low temperature and high temperature closure bars;   and where the said low temperature and high temperature fins are separated from one another by said parting sheets;   and where the said low temperature and high temperature fins are enclosed respectively by said low temperature and high temperature closure bars;   and where the two outermost layers of either the said low temperature fins and/or high temperature fins are enclosed by the said end plates;   and where the said functional elements constitute a set of elementary heat transfer layers for the said low temperature and high temperature fluid flows;   and where the said elementary heat transfer layers are disposed alternately along parallel planes in mutually perpendicular directions for low temperature and high temperature fluid flows;   and where a plurality of the said elementary heat transfer layers for low temperature and high temperature fluid flows together with the said two sets of inlet and outlet headers constitute a confined enclosure for segregated low temperature and high temperature fluid flows;   wherein the said core is entirely produced from one monolithic metallic block and is entirely devoid of any brazed joints;   and wherein all the said functional elements of the core, including the low temperature and high temperature fins, form its integral parts;   and wherein the said low temperature and high temperature fins are formed by a plurality of parallel thin channels cut out from the said block of metal;   
   
   
       2 . A compact plate and fin heat exchanger of  claim 1 , wherein the said core is partially produced from one monolithic metallic block and wherein all the said functional elements of the said core with the exception of the low temperature and high temperature fins are its integral parts; and
 wherein special slots are cut out in parallel planes and alternating in mutually perpendicular directions for alternate introduction of said low temperature and high temperature fin layers for the said low temperature and high temperature fluid flows; and where, in each of the said special slots, two braze filler metal foils are introduced to fully cover both of the fin layer faces; and   wherein the said fin layers together with the said braze filler foils are snugly fitting into the said special cut slots; and wherein the said low temperature and high temperature snugly fitted fin layer surfaces are brazed to the adjacent surfaces of the said special slots.   
   
   
       3 . A compact heat exchanger of  claim 2  wherein both sets of the said special slots for low temperature and high temperature fluid flows are fitted with corrugated fins. 
   
   
       4 . A compact heat exchanger of  claim 2  wherein the said special slots for low temperature and high temperature fluid flows are alternately fitted with corrugated and individual fins. 
   
   
       5 . A compact heat exchanger of  claim 2  wherein both sets of the said special slots for low temperature and high temperature fluid flows are fitted with individual fins.