Patent Publication Number: US-6990748-B2

Title: Method and apparatus for evaporating liquid from a product

Description:
RELATED PATENT APPLICATIONS 
   This patent application claims priority from prior U.S. Provisional Patent Application Ser. No. 60/502,393 filed on Sep. 12, 2003, entitled METHOD AND APPARATUS FOR EVAPORATING LIQUID FROM A PRODUCT, the disclosure of which is incorporated herein in its entirety by this reference. 

   COPYRIGHT RIGHTS IN THE DRAWING 
   A portion of the disclosure of this patent document contains material that is subject to copyright protection. The applicant has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure, as it appears in the Patent and Trademark Office patent file or records, but otherwise reserves all copyright rights whatsoever. 
   1. Technical Field 
   This invention relates to heat transfer apparatus, especially as may be employed for concentrating and drying operations. Such apparatus is particularly well suited to sanitary applications, such as processing and packaging of foods. 
   2. Background 
   Methods and apparatus for the transfer of heat through a thin, infrared transparent film between a flowable product such as sludge, slurry, extract, juice, or other like product, and a heated or chilled liquid, have been taught in previous patents used in earlier development of our equipment, namely U.S. Pat. No. 4,631,837, issued Dec. 30, 1986 for a Method and Apparatus for Drying Fruit Pulp and the Like, and U.S. Pat. No. 6,047,484, issued Apr. 11, 2000, for a Method and Apparatus for Evaporating Liquid from a Product, and the disclosures of each of these U.S. patents is incorporated herein in their entirety by this reference. However, the challenge of providing a clean, sanitary environment for evaporation of liquid from a product, or for chilling a product, especially as practiced using a thin flexible film material, has continued to require development of new apparatus and methods, especially to take advantage of such apparatus when applied to food preparation. And concurrently, the need for sanitary systems that can be easily cleaned to a high level of purity, i.e., freedom from biological contamination, has continued to be of utmost importance to food processors. Thus, the ability to provide an improved, easily cleanable and easily maintainable evaporation or chilling apparatus for sanitary, cleanable applications, such as drying of fruits or other foods, has become increasingly important. This is especially true at locations which are making foods such as fruit leathers from a pulp or fruit juice mass, which, after drying, must remain viable for long storage periods. Also, in order to pass governmental inspections in most, if not all locales, easily cleaned sanitary equipment is mandatory. Thus, there has been an increasing demand for high performance drying and evaporation systems, including for designs such as those taught in the prior art patents that were just noted above, but that demand has been coupled with a further requirement to provide an easily replaceable heat transfer element useful when drying a food product. Consequently, this disclosure provides description of a novel heat transfer apparatus, and of the novel equipment in which such heat transfer apparatus can be employed. 

   
     BRIEF DESCRIPTION OF THE DRAWING 
     In order to enable the reader to attain a more complete appreciation of the invention, and of the novel features and the advantages thereof, attention is directed to the following detailed description when considered in connection with the accompanying figures of the drawing, wherein: 
       FIG. 1  side cross-sectional view of one embodiment of the replaceable heat transfer apparatus taught herein, showing in the sectioned illustrations the inlet flood box, the pair of flexible planar polyester sheets, an outlet manifold, as well as the adjustably inclined support tray, and a retractable hood, and a working product being distributed to the upper flexible planar sheet and flowing down to a working product collection pan. 
       FIG. 2  provides a perspective photograph of one embodiment for an inlet floodbox (at the top) and an outlet manifold (at the bottom), showing the vacuum outlet on the upper edge of the outlet manifold, as well as a pair of sanitary quick disconnect type outlets for discharging a heat transfer fluid from the outlet manifold. 
       FIG. 3  provides a photograph of an inlet floodbox. 
       FIG. 4  provides a perspective view of one embodiment for an inlet floodbox (at the top) and an outlet manifold (at the bottom), showing the vacuum outlet on the upper edge of the outlet manifold, as well as a pair of sanitary quick disconnect type inlets in the inlet floodbox, as well as a pair of sanitary quick disconnect type outlets for discharging a heat transfer fluid from the outlet manifold. 
       FIG. 5  provides a perspective view of one embodiment for an inlet floodbox (at the top) and an outlet manifold (at the bottom), showing the liquid distribution passageways in the inlet floodbox, and the liquid collection passageways in the outlet manifold, as well as mounting locations for bolts which are used to affix, via suitable clamps, upper and lower flexible planar sheets to the apparatus, as further described herein. 
       FIG. 6  is a perspective view of one embodiment of an inlet floodbox, showing the upper mounting clamp used to secure the upper flexible planar sheet to the inlet floodbox, as well as some of the fasteners (here, bolts) used to space the upper flexible planar sheet outward from the liquid distribution passageways. 
       FIG. 7  shows a heat transfer apparatus as taught herein, with the support structure, adjustably inclinable support tray, a replaceable heat transfer module in operable location on the support tray, and the retractable air hood in an up, normally non-operating position wherein it is distanced away from the replaceable heat transfer module. 
       FIG. 8  is a view similar to the view first shown in  FIG. 7 , but now showing additional details of the orientation of the retractable hood, and a safety latch used to secure the retractable hood in an open condition without dependence on an telescoping cylinder; also shown is an air actuated cylinder, such as a Bimba® brand (or equivalent) which can be utilized to increase or decrease the angle at which the support tray is inclined. 
       FIG. 9  is a photograph of the lower end portion of the replaceable heat transfer module, showing the use of a tail collection sheet, where the tail collection sheet extends past the outlet manifold for a preselected distance in order to carry the working product to a working product collection pan; also visible in this view are the upwardly and outwardly sloping sidewall portions of the support tray, which cradle the evaporator envelope marginal portions to provide a flat bottomed V-shape area to contain the working product during evaporation. 
       FIG. 10  is a close up photograph of a small part of the lower end portion of the replaceable heat transfer module first shown in  FIG. 9 , now showing in additional detail the use of a tail collection sheet, where the tail collection sheet extends past the outlet manifold for a preselected distance in order to carry the working product to a working product collection pan. 
       FIG. 11  is a close up photograph of a portion of the inlet floodbox, showing the use of a lower inlet clamp to secure the lower flexible planar sheet to the inlet floodbox. 
     In  FIG. 12 , both the lower flexible planar sheet and the upper flexible planar sheet are shown affixed in a fluidly sealed condition to the inlet floodbox; also seen at a first end of the inlet floodbox is a marginal area of the evaporator envelope which extends transversely beyond the first end of the inlet floodbox. 
       FIG. 13  illustrates the flexible nature of the upper and lower flexible planar sheets, and provides an indication that the replaceable heat transfer module, including the inlet floodbox, and outlet manifold may be folded or rolled into a compact package for shipment as a replacement kit. 
       FIG. 14  further illustrates the flexible nature of the upper and lower flexible planar sheets, and provides confirmation that the replaceable heat transfer module, including the inlet floodbox, and outlet manifold may be folded or rolled into a compact package for shipment as a replacement kit. 
       FIG. 15  shows a heat transfer apparatus utilizing a replaceable heat transfer module, showing the adjustably inclinable support tray, and a retractable hood. 
     In  FIG. 16 , a sight window provided in the retractable hood portion; several of such windows may be provided (see  FIG. 15 , for example) to allow an operator to view the working product located on the evaporator envelope during evaporation or product chilling operations. 
     One embodiment for a pivot joint between the support tray and the retractable hood is illustrated in  FIG. 17 , which also shows the working product supply line, through which working product is sent to the working product distributor. 
     In  FIG. 18 , the closed, working position of the retractable hood is illustrated, showing how the sweep air plenum portion of the retractable hood is brought into close mating relationship with the lateral edges of the support tray, so that sweep air is substantially prevented from escape during countercurrent movement of sweep air from the inlet air plenum to the outlet air plenum of the retractable hood. 
       FIG. 19  is similar to  FIG. 18 , also showing the retractable hood in the closed, working position, but now showing the inlet air ducts which provide air to the inlet air plenum, the sweep air plenum wherein sweep air is brought into contact with the working product, the outlet plenum from which the outlet air ducts emerge, and a plurality of drain lines from which condensate or entrained moisture is collected from the outlet air ducts. 
     In  FIG. 20 , the inlet end of the support tray is shown, including the inlet floodbox support, as well as a pair of hoses which are connected to a pair of inlets to the inlet floodbox via quick disconnect sanitary fittings. 
       FIG. 21  provides a perspective photograph of the replaceable heat transfer module in working position on a support tray, and further illustrates the use of a plurality of removable, cleanable tray units, which in this embodiment are each rectangular stainless steel tray units. 
       FIG. 22  shows the outlet manifold support at the lower end of the support tray, with the outlet manifold supported therein in a working position, with a plurality of outlet hoses affixed to outlets via quick disconnect fittings, and with a vacuum line connected to a vacuum outlet on the upper side portion of the outlet manifold. 
       FIG. 23  is similar to  FIG. 22 , but now shows the outlet trough and the outlet nozzle from the product collection trough, and the product outlet hose. 
     In  FIG. 24 , additional operating equipment is shown, including a product tank for receiving working product from the product outlet hose just seen in  FIG. 23 , and a positive displacement pump suitable for pumping a working product through the product supply hose up to the working product distributor. 
       FIG. 25  shows the use of a toothed latch for a support tray lock, as well as the use of an actuation cylinder to move a retractable locking pin from an engaged, locked position to a retracted, unlocked position. 
       FIG. 26  illustrates a telescoping safety latch for securing the retractable hood independently of actuators which raise and lower the retractable hood; a nested extensible arm is extended and retracted via a small actuating cylinder to place the safety latch in an extended, locking position, or retract the safety latch into an unlocked position wherein the retractable hood is moveable. 
       FIG. 27  illustrates the details of portions of one embodiment for a replaceable heat transfer module, specifically illustrating the lower flexible planar sheet and the upper flexible planar sheet and construction details which provide a fluid chamber. 
       FIG. 28  illustrates the details of yet another embodiment for a replaceable heat transfer module, wherein instead of an overlapping seam as shown in  FIG. 1 , the outlet ends of the upper flexible planar sheet and the lower flexible planer sheet are spaced apart by a face block on the outlet manifold, and through which face block the heat transfer fluid exits, and against which face block the outlet ends of the upper and lower flexible planar sheets are secured. 
       FIG. 29  illustrates, in partial view, a downstream view of the face block for an outlet manifold as just depicted in  FIG. 28 , now showing the individual fluid outlets and the upper and lower flexible planar sheets. 
   

   The foregoing figures, being merely exemplary, contain various elements that may be present or omitted from actual implementations and process configurations of the replaceable heat transfer module and the heat transfer module in which the module may be used for heating, evaporation, or cooling, depending upon the circumstances. An attempt has been made to draw the figures in a way that illustrates at least those elements that are significant for an understanding of the various embodiments and aspects of the invention. However, various other elements of the unique replaceable heat transfer module are also shown and briefly described to enable the reader to understand how various features, including optional or alternate features, may be utilized in order to provide a simple, cleanable, sanitary heat transfer module apparatus that can be manufactured in a desired size and configuration for providing a long lasting and superbly performing heating, cooling, or evaporation system. 
   DETAILED DESCRIPTION 
   The improvements described and claimed herein relate to methods and apparatus for providing a modular, replaceable, cleanable, sanitary heat transfer module for heating, concentrating or cooling products. More specifically, the improvement described herein is to provide a unique cleanable and replaceable heat transfer module  30 , and an improved heat transfer apparatus in which the heat transfer module can be advantageously employed for chilling, heating, or evaporation of a selected working product. 
   As seen in  FIG. 1 , the heat transfer module  30  includes an inlet flood box  32 , an outlet manifold  34 , and an evaporator envelope  36  in a fluid tight relationship therebetween. The heat transfer module  30  is advantageously employed in an adjustably inclinable platform base support tray  40 . To assist in achieving the desired heating, cooling, or evaporation result, a retractable hood  42  may be provided for the supply of sweep air  44 . As illustrated in this embodiment, sweep air  44  may be configured to move countercurrently to the gravity flow of working product  50  downward across the upper side  51  of an upper sheet  52  of flexible planar material. A lower sheet of flexible planar material  54  is also provided. Each of the upper  52  and lower  54  flexible planar sheets may be provided in a suitable flexible substance. Suitable embodiments include infrared permeable materials, and more preferably, infrared transparent materials. In the embodiment illustrated, the use of a thin polyester, for example, Mylar® brand polyester film, formerly sold by E.I. du Pont de Nemours and Company, and now available from the DuPont joint venture, DuPont Teijin Films, has been taught, since such films are practically transparent to far infrared radiation and thus are advantageous especially for heat transfer applications. Also, such films are suitable for food grade service, and in heating or cooling service, with a variety of working product substances, for example, (a) liquids, or (b) slurries, (c) pumpable high viscosity materials, or (d) any substance or product material where particulates are included in (i) a liquid, (ii) a slurry, or (iii) a pumpable high viscosity material. As a further example, common working products which may be advantageously concentrated may include foods such as fruit or berry mixtures, such as raspberry puree. 
   The replaceable heat transfer module  30  is useful for providing thermal contact between a first heat transfer fluid  60  such as water, and a working product  50 . The first heat transfer fluid  60  and the working product  50  are provided at differing temperatures. 
   At the upper end  56  of the heat transfer module  30 , an inlet floodbox  32  includes at least one inlet  62  for entry (see reference arrow  63  in  FIG. 1 ) of the first heat transfer fluid  60  into the heat transfer module  30 . The inlet floodbox  32  includes a plurality of fluid distribution passageways  62  for discharge of the first heat transfer fluid  60 . 
   At the lower end  66  of the heat transfer module  30 , an outlet manifold  34  is provided. The outlet manifold includes a plurality of fluid collection passageways  64  for collection of the first heat transfer fluid  60  after the first heat transfer fluid  60  passes through the evaporator envelope  36 . The outlet manifold  34  includes at least one outlet  68  through which the first heat transfer fluid  60  is discharged (see reference arrow  69  in  FIG. 1 ). Two outlets  68  can be provided spaced equidistant from first  134  and second  138  ends of outlet manifold  34 . 
   Extending in a fluid tight relationship between the plurality of fluid distribution passageways  62  and the plurality of fluid collection passageways  64 , a thin, elongate evaporator envelope  36  is provided. The evaporator envelope has a lower flexible planar sheet  54  and an upper flexible planar sheet  52 . The upper flexible planar sheet  52  and said lower flexible planar sheet  54  each having inner surfaces,  72  and  74 , respectively, located in a back-to-back spaced apart relationship. In other words, two sheets of Mylar polyester are laid flat one over the other. The evaporator envelope  36  has an upper end  75  wherein the lower  54  and said upper  52  flexible planar sheets are fluidly sealed to the inlet floodbox  32 . The evaporator envelope  36  has a lower end  76  wherein the lower  54  and upper  52  planar sheets are fluidly sealed to the outlet manifold  34 . As seen in  FIG. 27 , at a first edge portion  80  and at a second edge portion  82 , a narrow strip of the lower flexible planar sheet  54  and a narrow strip of the upper flexible planar sheet  52  are fluidly sealed together. As illustrated in  FIG. 27 , at the fluid seal along first edge portion  80 , a first joint  84  is provided between lower flexible planar sheet  54  and upper flexible planar sheet  52 , which is bonded or sealed by use of an adhesive, such as a suitable pressure sensitive adhesive  86 , shown slightly extended for purposes of illustration only in  FIG. 27 . Similarly, at the fluid seal along second edge portion  82 , a second joint  88  is provided between lower flexible planar sheet  54  and upper flexible planar sheet  52 . The second joint  88  is bonded or sealed by use of an adhesive, such as by using a suitable two sided adhesive tape  86 , again shown slightly extended for purposes of illustration only in  FIG. 27 . 
   In one embodiment, as shown in  FIG. 1 , and  FIGS. 7–10 , and  FIG. 27 , a tail collection sheet  90  is provided. The tail collection sheet  90  extends, in a downstream direction, past the outlet manifold  34  for a preselected distance D in order to carry a working product  50  to a working product collection pan  94 . As illustrated in the embodiment shown in  FIGS. 1 and 27 , the tail collection sheet  90  is an integral extension of the upper flexible planar sheet  52 . In such a situation, the upper flexible planar sheet  52  has an upstream or top end portion  100 , and a downstream or bottom end portion  102 , and in such a case, the bottom end portion  102  comprises an upstream edge fluidly sealed at a third joint  104  to the top end portion  100 . Thus, in this embodiment, the bottom end portion  102  of the upper flexible planar sheet  52  is the component which provides the downstream edge fluidly sealed to the outlet manifold  34 . This configuration is illustrated in  FIGS. 1 and 27 . As shown in  FIG. 1 , the third joint  104  between the bottom end portion  102  and the top end portion  100  is spaced upstream a preselected distance from the outlet manifold  34 . In one embodiment, the preselected distance E is in the range from about 20 centimeters to about one meter. 
   As see in  FIGS. 2 and 3 , the fluid distribution passageways  62  in the inlet floodbox  32  are arranged to distribute the first heat transfer fluid  60  substantially uniformly along the upper end  75  of  FIG. 1  of the evaporator envelope so that the first heat transfer fluid  60  descends in a continuous film between the inner surfaces  74  and  72  of the lower and upper flexible planar sheets, respectively. The first heat transfer fluid  60  is provided to inlet floodbox  32  via an upflow configuration to at least one inlet  110 , and thence through the inlet floodbox  32  past internal baffles  112  (see  FIG. 1 ), and thence to the liquid distribution passageways  62 . The internal baffles  112  are oriented to break the force of the first heat transfer fluid  60  entering through each one of the inlets  110  provided, so as to evenly distribute the first heat transfer fluid  60 . A pair of inlets  110  can be provided, spaced apart equidistant between first  132  and second  136  ends of the inlet floodbox  32 , which is oriented transversely with respect to the flow of the first heat transfer fluid  60 , and thus to the length of evaporator envelope  36 . As illustrated in  FIG. 1 , and as perhaps best visualized from  FIG. 3 , the inlet floodbox  32  has an upper internal headspace  120  which is configured to contain a trapped air bubble, so as to provide for a free weir action of water exiting through the liquid distribution passageways  62 . A trough portion  122  provides a liquid reservoir within inlet floodbox  32 . 
   Overall, in one embodiment, the replaceable heat transfer module may be provided in a configuration wherein the lower  54  and said upper  52  flexible planar sheets have a thickness on the order of millimeters or fractions thereof (for example, a polyester sheet with a thickness of about 3 to 8 mils may be useful in some applications). The internal working space for carriage of the first heat transfer fluid  60 , between the inner surface  74  of the lower flexible planar member  54  and the inner surface  72  of the upper flexible planar member  52  is of a size on the order of centimeters. The overall evaporator envelope has a length L in  FIG. 27 , between the inlet floodbox  32  and the outlet manifold  34 , on the order of meters, such as in the 4 to 10 meter range, though it may be shorter or longer than this range, depending on the application. 
   To help secure the working product and avoid loss, in one embodiment as illustrated in  FIG. 27 , the evaporator envelope  36  has a first marginal width area M 1  extending transversely beyond a first end  132  of the inlet floodbox  32  and a first end  134  of the outlet manifold  34 , to edge  80 . Likewise, on the other side, evaporator envelope  36  has a second marginal width M 2  extending transversely beyond a second end  136  of the inlet floodbox  32  and a second end  138  of the outlet manifold  32 , out to edge  82 . For clarity, in such a case, the evaporator envelope  36  is considered to also include a base  140  of width B 1  and which runs, lengthwise substantially between the inlet floodbox and said outlet manifold. In such a situation, as better illustrated in  FIGS. 7 ,  9 , and  15 , the first marginal width M 1  and second marginal width M 2  are sized and shaped for sloping outwardly and upwardly from the base width B 1  to provide a generally flat bottomed V-shaped trough running from the inlet floodbox  32  to the outlet manifold  34  for containment of a selected working product  50 . 
   As indicated in  FIG. 1 , the inlet floodbox  32  has inlet upper clamp or clamp plate  150 , which secures the upper flexible planar sheet  52  to the inlet floodbox  32 . Also, the inlet floodbox  32  has an inlet lower clamp  152 , which secures the lower flexible planar sheet  54  to the inlet floodbox  32 . As seen in  FIG. 6 , for example, the inlet lower clamp  152  is secured to the inlet floodbox  32  with a plurality of upwardly protruding fasteners  160 . The upwardly protruding fasteners  160  support the upper flexible planar sheet  52  a spaced apart distance from the upper surface  162  of cover plate portion  164 , and thus from the plurality of fluid distribution passageways  62 , so that the first heat transfer fluid  60  can freely flow from the fluid distribution passageways  62  to the evaporator envelope  36 . In one embodiment illustrated, suitable fasteners  160  may be bolts with heads. 
   In a similar fashion, as shown in  FIG. 1 , to the inlet floodbox construction, at the outlet manifold  34 , an outlet lower clamp  170  is provided which secures the lower flexible planar sheet  54  to the outlet manifold  34 . Also provided at the outlet manifold  34  is an outlet upper clamp plate  172  which secures said downstream edge  174  of the bottom end portion  102  of the upper flexible planar sheet to the outlet manifold  34 . In one embodiment, the outlet lower clamp  170  is secured to the outlet manifold  34  with a plurality of upwardly protruding fasteners  180 . The upwardly protruding fasteners  180  support the lower end portion  102  of the upper flexible planar sheet  52  a spaced apart distance from the upper surface  181  of outlet lower clamp  170  (and thus even further from upper surface  182  of cover plate portion  184  of the outlet manifold  34 ), and thus from the plurality of fluid collection passageways  64 , so that the first heat transfer fluid  60  can freely flow from the evaporator envelope  36  and into the fluid collection passageways  64 . Outlets  68  from the outlet manifold  34  can include a quick connect sanitary fitting. Such fittings are useful generally for the inlets  110  also, as well as joints in the working product flow circuit. 
   Turning now to  FIG. 27 , the inlet face (plate) cover portion  164  has an upper end  190  and lower end  192 , flow-wise, and the liquid distribution passageways  62  are provided closer to the lower end  192  than to said upper end of the inlet face cover portion  164 . In one embodiment, this split may be located at roughly one-third of the distance between lower end  192  and upper end  190 . Likewise, in the outlet manifold  34 , the outlet manifold outlet face (plate) cover portion  184 , the liquid collection passageways  64  are provided in the outlet face (plate) cover portion  184 . The outlet face cover portion  184  has an upstream  200  end and a downstream end  202 , and the liquid collection passageways  64  are provided in the inlet face cover portion  184  closer to the upstream end  200  than to the downstream end  202 . Again, in one embodiment, the location of the passageways  64  can be about one third of the way along the inlet face cover portion  184 , flow-wise, or on the upstream end. 
   Although a variety of shapes may be utilized for fluid distribution and collection structures, in one embodiment illustrated for example in  FIG. 5 , each one of the plurality of fluid distribution passageways  62  and each one of the plurality of fluid collection passageways  64  are configured in a substantially parallelepiped orientation with smooth, rounded corner portions, and wherein the long portion of parallelepiped passageways extends in a side to side orientation with respect to the evaporator envelope  36 . 
   As shown in  FIG. 4 , the outlet manifold  34  is shaped as an elongate trough having upper edge portions  210  and  212 . As indicated in  FIGS. 2 ,  4 , and  23 , the outlet manifold further includes at least one fluid outlet  214  passageway adjacent at least one of the upper edge  212  which is adapted for vacuum service, so that vacuum may be applied to remove air from the outlet manifold  34  when the outlet manifold is filled with a heat transfer fluid such as hot or chilled water. 
   When the replaceable heat transfer module  30  is filled with a heat transfer fluid, the evaporator envelope  36  is strong, monocoque structure. However, as seen in  FIGS. 13 and 14 , the lower  54  and upper  52  flexible planar sheets are sufficiently flexible and resilient that the replaceable heat transfer module  30 , when not containing a heat transfer fluid, can be folded or rolled into a compact, shippable package including the evaporator envelope  36 , the inlet floodbox  32 , and the outlet manifold  34 . 
   Attention is now directed to  FIGS. 15  though  26 , where further details are shown of an exemplary heat transfer apparatus  300  designed for utilization of the replaceable heat transfer module  30  disclosed above. The heat transfer apparatus  300  has a structural base  302  and an adjustably inclinable support tray  40  that is adjustably affixed to the structural base  302 . The adjustably inclinable support tray  40  is sized, shaped, and configured to support in an operational position the replaceable heat transfer module  30  just described. Thus, the inclinable support tray  40  has an inlet floodbox support  310 , an outlet manifold support  312 , and extending substantially between the inlet floodbox support  310  and the outlet manifold support  312 , a generally flat support pan  320  having a length and a width. The replaceable heat transfer module  30  is adjustably affixed to the support tray  40 , and tension between the inlet flood box  32  and the outlet manifold  34  may be adjusted as operation begins and or continues. 
   A retractable hood  42  is provided. The retractable hood  42  includes an air inlet plenum  322 , an air outlet plenum  324 , and extending between the air inlet plenum  322  and the air outlet plenum  324 , a sweep air plenum  326 . The sweep air plenum  326  is configured to substantially match the length and width of the inclinable support tray  40 . The hood, including the sweep air plenum  326 , is retractably affixed to the structural base  302 . As illustrated in  FIGS. 15 ,  18 ,  19 , and  21 , the sweep air plenum  326  has first  328  and second  330  side portions configured for close fitting mating engagement with the support pan  320 , so that air passing through the sweep air plenum  326  is substantially prevented from escaping outward between the sweep air plenum  326  and the support pan  320 . Usually (but not necessarily) the inlet air duct  340  and the outlet air duct  342  are arranged for counter-current flow of air with respect to flow of the first heat transfer fluid  60  and the working product  50 , which flow co-currently, by gravity. As seen in  FIG. 18 , the outlet air ducts may include a drain outlet  350 , which is configured to trap for discharge any liquids arriving at or condensing in the air outlet duct  342 . 
   As seen in  FIG. 1  and  FIG. 17 , the adjustably inclinable support tray  40  and the retractable hood  42  are pivotally joined at pivot pin  360 . As indicated, the support tray  40  and the retractable hood  42  are pivotally joined adjacent the inlet floodbox  32  support. As indicated in  FIG. 1 , the support tray  40  is adjustable to a selected downwardly sloping angle alpha (a), with respect to a horizontal reference plane  362 . In various embodiments, the selected downwardly sloping angle alpha (α) can be established between about 30 degrees and about 45 degrees. However, for a particular application, the selected downwardly sloping angle alpha (α) may be larger than about 45 degrees. Or for other heat transfer situations, the selected downwardly sloping angle alpha (α) may be less than about 30 degrees. For movement of the support tray  40 , at least one adjustable support tray actuator  370  is provided. The support tray  40  is adjustably raised and lowered to said preselected angle alpha (α) by movement of the at least one support tray actuator  370 . In the embodiment shown in  FIG. 18 , the at least one adjustable support tray actuator  370  is a telescopic cylinder, which may be provided in a pneumatic or hydraulic actuator. One convenient design is to use air actuated cylinders. 
   To enhance safety, a support tray lock  366  may be provided. As seen in  FIG. 25 , one embodiment for such a lock includes a toothed latch  367  and a retractable pin  368 . The retractable pin  368  is sized and shaped for movement between (1) a locking position in which the pin rests in the toothed latch  367  to lock the support tray  40  at a selected first position, and (2) a retracted position, in which the support tray  40  can be moved to another desired angle alpha (α). For convenience, the retractable pin  368  is moved by a hydraulic or pneumatic actuator  369 . 
   With respect to the hood  42 , as indicated in  FIG. 1 , the retractable hood  42  is pivotable (at pivot pin  360 ) to a selected upwardly sloping angle beta (β), with respect to the support tray  40 . To raise the hood  42 , at least one retractable hood actuator  372  is provided. Thus, the retractable hood actuator  372  is adjustably raised and lowered to a preselected angle beta (β) by movement of the retractable hood actuator(s)  372 . Such actuators may be a telescopic cylinder, such as a pneumatic or hydraulic actuator. As seen in  FIG. 26 , to enhance safety, on structural base  302 , a retractable hood safety catch  376  can be provided. The safety catch  376  is movable into a hood  42  support position to secure the retractable hood  42  in an open position independently of the actuators  372 . Safety catch actuators  378  can be provided for hydraulically or pneumatically moving the safety catch  376 . To see inside of the hood  42  during operation, one or more sight windows  379  can be provided. The sight windows  379  can be sized and shaped to allow viewing of flow of working product along the evaporator envelope  36 . 
   For operation, to distribute working product on the evaporator envelope  36 , adjacent the inlet floodbox  32  and in close proximity to the upper flexible planar sheet  52 , a working product distributor  380  is provided. The working product distributor  380  configured to distribute a working product  50  on to the upper flexible planar sheet  52 , so that the working product  50  may flow by gravity downward along the upper flexible planar sheet  52 . At the lower end, a working product collection pan  94  is provided to pick up working product as it leaves the tail collection sheet  90 . 
   Turning now to  FIG. 24 , details of the method of use are seen. A product tank  400  is fluidly connected to receive working product  50  collected by the working product collection pan  94 . A positive displacement pump  402  is provided, wherein the pump  402  has an inlet  404  configured to receive working product  50  from the product tank  400 , and an outlet  406  configured to discharge working product  50  to the working product distributor  380 . 
   As seen in  FIG. 21 , and noted schematically in  FIG. 27 , the evaporator envelope  36  has a first marginal width M 1  extending transversely beyond the first end of the inlet floodbox and the first end of the outlet manifold, and lengthwise from the inlet floodbox to the outlet manifold. Also, a second marginal width M 2  is provided between the second end of the inlet floodbox and the second end of the outlet manifold, and lengthwise between the inlet floodbox and the outlet manifold. Since the support tray  40  has, transversely, upwardly and outwardly extending sidewall portions  410  and  412  that extend from lateral edges of the support pan  320 , the sidewall portions  410  and  412  are configured to provide a generally flat trough with sloping sides to carry working product. Thus, the evaporator envelope  36  conforms to such shape, since the marginal width M 1  and M 2  of the evaporator envelope are sized and shaped to generally match the sidewall portions  410  and  412  and thus the evaporator envelope slopes outwardly and upwardly from the support pan  320 . As seen in  FIG. 21 , the support pan portion  320  of the support tray  40  can be provided with a plurality of removable, cleanable tray portions  420 . 
   Turning now to  FIG. 28 , the details of yet another embodiment for a replaceable heat transfer module  30 ′ are shown, Here, a face block  422 , is provided for outlet module  34 ′. Instead of an overlapping seam for the bottom of the heat transfer envelope, as shown in  FIG. 1 , the outlet end  52   O  of the upper flexible planar sheet and the outlet end  54   O  of the lower flexible planer sheet are spaced apart by a face block  422  on the outlet manifold  34 ′. The heat transfer fluid  60  passes through and exits outward via orifices  423 , defined by edge walls  424 . Heat transfer fluid  60  thence flows into the interior of outlet manifold  34 ′. In this embodiment, the outlet end  54   O  of the lower flexible planar sheet  54 ′ is secured against seal face  425  by a lip  426  of face block  422  and fasteners such as bolts  180 ′ and accompanying nuts  181 ′. The orifices  423  and their edge walls  424  are better seen in  FIG. 29 . Also seen in  FIG. 29  is how fasteners  180 ′ secure lip  426  against lower planar sheet  54 ′. Likewise, the lower end  52   O  of the upper flexible planar sheet  52 ′ is secured against sealing face  428  on face block by outlet upper clamp  172 ′, which has a lower side  430  which presses against lower end  52   O  of the upper flexible planar sheet  52 ′, and thence into the sealing face  428  of block  422 . Thus, in this fashion, 
   The heat transfer apparatus  300  provides a tool for practice of a process for evaporation of liquid from a working product  50 . The working product can be a liquid, or a slurry, or pumpable high viscosity material, or any substance or product material where particulates are included in a liquid, a slurry, or a pumpable high viscosity material. The process involves providing a heat transfer apparatus as described herein, including a retractable hood as set forth herein, and placing the hood in a working location in close proximity to the support tray, configured to substantially preclude sweep air from escaping. A first heat transfer fluid, such as hot water, is introduced into the inlet floodbox. A flow of the first heat transfer fluid at a preselected inlet temperature is established. A working product is distributed on the evaporator envelope. The working product is allowed to flow by gravity to a working product collection pan. Solvent removed from the working product is captured in a sweep air stream running countercurrent to the flow of the working product. The angle alpha of the support tray  40  can be adjusted to maintain desired throughput and concentration or dryness of the working product. In one embodiment the process may be utilized on a food material. Food materials especially suited for processing in the apparatus include fruit mixtures, or berry mixtures, or juices. As a further enhancement, the sweep air stream may be conditioned to a desired temperature and humidity level to assist removal of solvent from the working product. Or, the sweep air stream may be simply ambient air, if suitable. 
   In yet another embodiment, a working product may be chilled in the heat transfer apparatus  300 . In such a case, the first heat transfer fluid may be chilled water or a suitable brine composition. As when the heat transfer apparatus is utilized for heating or drying, when chilling is desired, the sweep air stream may be conditioned to a desired temperature and humidity level to assist I in chilling of the selected working product. 
   Although various aspects and elements of the invention are herein disclosed for illustrative purposes, it is to be understood that the replaceable heat transfer module, and the method of use of the replaceable heat transfer module in thin film heating, drying, evaporation, and chilling systems, are important improvements in the state of the art of devices and methods for handling materials in thin film heat transfer systems with cleanable, sanitary, replaceable heat transfer components. Although only a few exemplary aspects have been described in detail, various details are sufficiently set forth in the figures of the drawing and in the specification provided herein to enable one of ordinary skill in the art to make and use the invention(s), which need not be further described by additional writing in this detailed description. Importantly, the aspects and embodiments described and claimed herein may be modified from those shown without materially departing from the novel teachings and advantages provided as described herein, and may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. It is especially pointed out that the size, and extent of a desirable heat transfer module, and especially the shapes for liquid distributors and liquid collectors, or the length and width of an evaporation envelope, and the amount of material handled thereby, will vary widely based on the nature of the working products provided, and based on the chilling, heating, or evaporation conditions used, especially when a residual solvent (such as water) is removed. Therefore, the embodiments presented herein are to be considered in all respects as illustrative and not restrictive. As such, this disclosure is intended to cover the structures described herein and not only structural equivalents thereof, but also equivalent structures. Numerous modifications and variations are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the invention(s) may be practiced otherwise than as specifically described herein. Thus, the scope of the invention(s) is as described herein and as set forth in the appended claims, and as indicated by the drawing and by the foregoing description, is intended to include variations from the embodiments provided which are nevertheless described by the broad interpretation and range properly afforded to the plain meaning of the language of the claims set forth below.