Multi-cavity tubes for air-over evaporative heat exchanger

Abstract

An air-over evaporative heat exchanger with multi-lobed or “peanut” shaped tubes replacing conventional round or elliptical tubes. The tubes have a narrow horizontal cross section and tall vertical cross section to allow the multiplication of surface area in the same coil volume while maintaining or increasing the open-air passage area. This configuration allows the coil to have an overall external heat transfer coefficient much higher than a conventional coil, while the tube shape allows the use of thinner material, reducing the weight and cost of the heat exchanger.

1 . An air-over evaporative heat exchanger coil comprised of:
 a plurality of multi-lobed tubes arranged in a tube bundle.   
     
     
         2 . The device according to  claim 1  wherein the multi-lobed tubes have exactly two lobes. 
     
     
         3 . The device according to  claim 1  wherein the multi-lobed serpentine tubes have exactly three lobes. 
     
     
         4 . The device according to  claim 1  with 100%-300% of the tube surface area of a coil having the same external dimensions with 0.85 inch elliptical tubes. 
     
     
         5 . The device according to  claim 1  with 25%-150% of the open-air passage area of a coil having the same external dimensions with 0.85 inch elliptical tubes. 
     
     
         6 . The device according to  claim 1  wherein the major axis of the tube is tilted 0 to 25 degrees relative to vertical. 
     
     
         7 . The device according to  claim 2  wherein the major axis of the tube is tilted 0 to 25 degrees relative to vertical. 
     
     
         8 . The device according to  claim 3  wherein the major axis of the tube is tilted 0 to 25 degrees relative to vertical. 
     
     
         9 .- 13 . (canceled) 
     
     
         14 . The device according to  claim 1 , wherein said tubes are finned. 
     
     
         15 . (canceled) 
     
     
         16 . The device according to  claim 1 , said tubes having tube heights of 1.250 to 2.500 inches with lobe widths of 0.200 to 0.500 inches and tube wall width from 0.005 inches to 0.055 and wherein said tubes can withstand working pressure of 300 psi. 
     
     
         17 . (canceled) 
     
     
         18 . The device according to  claim 1 , said tubes having tube heights of 1.790 inches, a tube width at a widest cross-section of each lobe of 0.375 inches, and a tube wall width of 0.055 inches, and wherein said tubes can withstand working pressures of 300 psi. 
     
     
         19 . (canceled) 
     
     
         20 . The device according to  claim 1  wherein the multi-lobed tubes are straight and each length of straight multi-lobed tube is connected at a first end to a process fluid inlet header and at a second end to a process fluid outlet header. 
     
     
         21 . The device according to  claim 1  wherein the multi-lobed tubes are serpentine and each serpentine tube comprises a plurality of lengths connected at each end to adjacent lengths of the same serpentine tube by tube bends and wherein a first end of each said serpentine tube is connected at one end to a process fluid inlet header, and at a second end to a process fluid outlet header.