Oil free falling film heat exchanger
View Patent ↗A falling film plate type heat exchanger. The heat exchanger includes a pressure vessel surrounding an encapsulated stack of plates. Each plate has a primary fluid side and a secondary fluid side. The primary fluid will be a refrigerant—such as R-134 a . The secondary fluid will typically be water. A film of refrigerant is applied to the primary fluid side of each plate, where it evaporates by absorbing heat from the secondary fluid on the other side of the plate. The invention uses embossed patterns on the plates to direct the flow of the primary and secondary fluids in a desired pattern. Further, the primary fluid side of each plate has a roughened surface treatment to increase the effective surface area and thereby increase the heat transfer rate.
1. A heat exchanger for exchanging heat between a primary fluid and a secondary fluid, comprising: a. a vessel, including a primary fluid inlet, a primary fluid outlet, a secondary fluid inlet, and a secondary fluid outlet; b. a plurality of secondary flow channels, with each of said secondary flow channels being formed by a pair of plates having an inlet fluidly connected to said secondary fluid inlet and an outlet fluidly connected to said secondary fluid outlet; c. said plurality of secondary flow channels being fluidly connected in parallel; d. each of said plates having an outward facing primary fluid side; and e. a spray manifold fluidly connected to said primary fluid inlet, said spray manifold having a plurality of spray nozzles directed toward said outward facing primary fluid sides of said secondary flow channels, said spray nozzles directing a spray of said primary fluid against said outward facing primary fluid side of one of said secondary flow channels; a plurality of spray manifolds located in between said pairs of plates forming said secondary flow channels; wherein each of said spray manifolds is bound by a pair of mated spray plates, with each of said spray plates having an inward facing liquid primary fluid side and an outward facing evaporating primary fluid side; and wherein said spray plates and said plates are bonded together.
2. The heat exchanger as recited in claim 1 , wherein said plurality of secondary flow channels are in a vertical orientation.
3. The heat exchanger as recited in claim 2 , wherein said secondary fluid is forced through said secondary flow channels from bottom to top.
4. The heat exchanger as recited in claim 1 , wherein said primary fluid side of each of said plates is provided with an enhanced surface having a surface area at least an order of magnitude greater than an untreated surface.
5. A heat exchanger the exchanging heat between a primary fluid and a secondary fluid, comprising: a. a vessel, including a primary fluid inlet, a primary fluid outlet, a secondary fluid inlet, and a secondary fluid outlet; b. a plurality of secondary flow channels, with each of said secondary flow channels having an inlet fluidly connected to said secondary fluid inlet and an outlet fluidly connected to said secondary fluid outlet; c. said plurality of secondary flow channels being fluidly connected in parallel; d. each of said plurality of secondary flow channels being bounded by a pair of mated plates, with each of said plates having an inward facing secondary fluid side and an outward facing primary fluid side; e. said plurality of secondary flow channels being spaced apart to create a plurality of gaps between adjoining pairs of mated plates; f. a plurality of spray manifolds located in at least some of said plurality of gaps between said adjoining pairs of mated plates; and g. wherein each of said spray manifolds has a plurality of spray nozzles directed toward said outward facing primary fluid sides of said secondary flow channels, said spray nozzle directing a spray of said primary fluid against said outward facing primary fluid side of at least one of said secondary flow channels; wherein each of said spray manifolds is bounded by a pair of mated spray plates, with each of said spray plates having an inward facing liquid primary fluid side and an outward facing evaporating primary fluid side; and wherein said spray plates and said plates are bonded together.
6. The heat exchanger as recited in claim 5 , wherein said plurality of secondary flow channels are in a vertical orientation.
7. The heat exchanger as recited in claim 6 , wherein said secondary fluid is forced through said secondary flow channels from bottom to top.
8. The heat exchanger as recited in claim 5 , wherein said primary fluid side of each of said plates is provided with an enhanced surface having a surface area at least an order of magnitude greater than an untreated surface.
9. A heat exchanger for exchanging heat between a primary fluid and a secondary fluid, comprising:
a. a vessel, including a primary fluid inlet, a primary fluid outlet, a secondary fluid inlet, and a secondary fluid outlet;
b. a plurality of secondary flow channels, with each of said secondary flow channels having an inlet fluidly connected to said secondary fluid inlet and an outlet fluidly connected to said secondary fluid outlet;
c. said plurality of secondary flow channels being fluidly connected in parallel;
d. each of said plurality of secondary flow channels being bounded by a pair of mated plates, with each of said plates having an inward facing secondary fluid side and an outward facing primary fluid side;
e. said plurality of secondary flow channels being spaced apart to create a plurality of gaps between adjoining pairs of mated plates;
f. a plurality of spray manifolds located in at least some of said plurality of gaps between said adjoining pairs of mated plates;
g. wherein at least some of said spray manifolds have a plurality of spray nozzles directed toward said outward facing primary fluid sides of adjacent secondary flow channels, said spray nozzles directing a spray of said primary fluid against said outward facing primary fluid sides of said adjacent secondary flow channels; and
h. each of said spray manifolds being bounded by a pair of mated spray plates, with each of said spray plates having an inward facing liquid primary fluid side and an outward facing evaporating primary fluid side.
10. The heat exchanger as recited in claim 9 , wherein said plurality of secondary flow channels are in a vertical orientation.
11. The heat exchanger as recited in claim 10 , wherein said secondary fluid is forced through said secondary flow channels from bottom to top.
12. The heat exchanger as recited in claim 9 , wherein said spray plates and said plates are bonded together.
13. The heat exchanger as recited in claim 12 , wherein said spray plates and said plates are bonded together by brazing.
14. The heat exchanger as recited in claim 9 , wherein said primary fluid side of each of said plates is provided with an enhanced surface having a surface area at least an order of magnitude greater than an untreated surface.
15. The heat exchanger as recited in claim 9 , wherein:
a. each of said plates has an upper perimeter;
b. each of said pair of mated spray plates includes a primary fluid inlet fluidly connected to said primary fluid inlet in said vessel; and
c. each of said primary fluid inlets on said pair of mated spray plates lies above said upper perimeters of said plates.