Solar heat recovery control

Flow control arrangement for use in a heating process utilizing multiple heat sources at different temperatures to transfer heat to a selected fluid circulated through the sources including at least one first heat source at a first temperature and having a fluid inlet means to receive the fluid and fluid outlet means adapted to emit the fluid, first valve means to control flow of fluid to the first heat source inlet, at least one second heat source at a second temperature having fluid inlet means to receive the fluid and fluid outlet means to emit the fluid, second valve means to control flow of fluid to the second heat source, a source of fluid adapted to supply the fluid to the first and second valve means, conduit means connecting the second heat source fluid outlet with the first valve, conduit means connecting the first heat source fluid outlet with the second valve means and controller means to actuate the first and second valve means and the source of fluid to direct fluid flow to one of the first and second heat sources at the lowest temperature then to the heat source with the highest temperature.

BACKGROUND OF THE INVENTION 
The present invention relates to a control mechanism for controlling the 
flow of a heat transfer fluid in heat transfer relation serially through a 
series of heat sources where the fluid flow is directed first through the 
lower temperature heat sources and finally to the higher temperature heat 
sources. 
The present invention finds particular application in recovery of heat from 
solar energy receiving cells where multiple cells are set at different 
angles and attitudes relative to incident sunlight so that the different 
cells are heated to different temperatures depending upon the position of 
the sun relative to the cells. For example, the present invention finds 
application, for example in devices utilizing pyramidal-shaped solar 
panels where in many instances two panels receive energy from the sun but 
the angle of incidence is different on the two panels so that the panels 
are heated to different temperatures. 
Without direction for the flow of heat transfer fluid through such 
pyramidal solar cells, the outlet temperature from the cell is the average 
of the effective heat transfer temperature of the two cells and therefore 
maximum temperature heat transfer fluid is not obtained. 
In most prior art arrangements utilizing solar heat transfer, flat panels 
have been utilized where the panels have generally been located on, for 
example, a southward directed surface in the northern hemisphere and a 
northern directed surface in the southern hemisphere. In such arrangements 
the solar rays strike directly on the panel during a small portion of the 
day. During the majority of the day the solar rays strike the panel at an 
acute angle so the outlet temperature of the fluid from the panels varies 
during the day being the maximum at approximately the noon hour solar 
time, when the sun shines directly on the panel. 
In previous arrangements utilizing multiple panels the order of flow 
through the panels have been fixed so such devices have not been capable 
of providing the maximum available heat necessary and equally as important 
maximum temperature in the heat transfer fluid for an extended portion of 
the day. The outlet temperature from such solar cells is particularly 
critical when the solar cell is utilized to provide heat to be stored for 
use at a later time, for example, during the nighttime or when the daytime 
skies are cloudy or where a maximum temperature is required such as in 
water distillation. 
Prior art arrangements showing attempts to provide maximum solar energy are 
shown in several references, and the most pertinent known are discussed 
hereinafter. 
U.S. Pat. Nos. 4,121,566; 4,015,584; 4,011,855; and 3,321,012 show various 
arrangements of fixed parabolic reflectors to receive solar energy and 
reflect the energy to a collector. 
U.S. Pat. Nos. 3,996,917 and 3,884,217 illustrate arrangements which 
recognize the advantages of maximizing the period of direct incidence of 
solar radiation on the collector device but accomplish the objectives by 
mechanical means including a moveable reflector and drive means to cause 
the reflector to "track" the sun through its path. 
Likewise, U.S. Pat. Nos. 4,121,566; 3,986,489; and 4,085,731 show devices 
which in one way or another operate in response to a change in temperature 
of a reference either the collector or the liquid utilized for heat 
transfer. 
For example U.S. Pat. No. 4,121,566 teaches an arrangement where multiple 
parabolic reflectors are utilized and where the heat transfer fluid is 
withdrawn from a heat source only after it reached a preselected 
temperature. 
Even where solar cells having a geometric design other than a flat plate 
have been utilized such devices are subject to the movement of the sun and 
no device is known to provide an arrangement to maximize the outlet 
temperature from multiple fixed solar heated panels to provide heat for 
storage or even for other purposes including the provision of fresh water 
from sea water. 
SUMMARY OF THE INVENTION 
The present invention provides an improved control arrangement for the use 
in applications including solar heating application where at least two 
different sources of heat are provided to heat a fluid and where the fluid 
is passed serially and selectively through the heat exchange sources. 
Briefly, the present invention provides an advantageous, economical 
straightforward arrangement to control the flow of heat transfer fluid 
first through the cooler of the heat sources and then through the warmer 
of the heat sources to optimize heat reception and maximizing temperature. 
Devices in accordance with the present invention find useful application in 
the control of the heat transfer fluid through solar cells where the cells 
are disposed at different attitudes relative to the path of the sunlight 
so at least two of the solar panels are always exposed to, and heated by, 
the radiant energy of the sun. 
In such applications, maximum heat transfer to the heat transfer fluid is 
achieved by heating the heat transfer fluid in the lower temperature solar 
cells and then providing a final heating in the solar cell exposed to the 
most direct rays of sunlight. 
Prior art devices are known where similarly oriented flat solar panels or 
parabolic reflectors have been used to receive the radiant energy from the 
sun, to provide heat to a heat transfer medium and where the angle of 
incidence of the radiation from the sun strikes the panel at the optimum 
only for a short period during the day. 
On the contrary, devices in accordance with the present invention provide a 
flow control arrangement for solar panel arrangements where the optimum 
angle of incidence occurs two or more times during the traverse of the sun 
across the sky each day. 
More particularly, while the present invention can be utilized in other 
applications, it is particularly useful in solar heating devices for 
obtaining the maximum temperature and heat recovery possible from multiple 
heat sources disposed at different angles relative to the traverse of the 
sun to provide useful heat to heat storage arrangements. Further in some 
applications, it is possible to provide sufficient temperature in the heat 
transfer medium for example, where the heat transfer medium is ocean 
water, to provide for distillation or evaporation of water from the sea 
water and recovery of potable water. 
More particularly, the present invention provides an arrangement including 
at least one first heat source means having a heat transfer medium 
passageway therethrough with first source fluid inlet means and a first 
source fluid outlet means, first heat source valve means adapted to 
control the flow of heat transfer medium through the first heat source, at 
least one second heat source means having a fluid heat transfer medium 
fluid flow passageway therethrough having a second source fluid inlet 
means and a second source fluid outlet means, second heat source valve 
means adapted to control flow of heat transfer medium through the second 
heat source, first heat source means fluid outlet conduit connected 
between the first heat source means outlet and the second heat source 
valve means and second heat source means fluid outlet conduit connected 
between the outlet of the second heat source and the first heat source 
valve means, flow controller means to operate said first heat source valve 
means and second heat source valve means so that heat transfer medium 
selectively flows from the heat transfer medium supply means to the first 
source fluid inlet means and from first source fluid outlet to the second 
source means fluid inlet means and through the second heat source means to 
the second source means fluid outlet means when the temperature of the 
second heat source means is greater than the temperature of the first heat 
source means and from the heat transfer medium supply means to the second 
source fluid inlet means and from the second source fluid outlet means to 
the first source fluid inlet means and through the first source heat 
transfer medium passageway means to the first source fluid outlet means 
when the temperature of the first heat source is greater than the 
temperature of the second heat source. 
It will be recognized that the foregoing discussion and the description 
hereinafter provide only examples of arrangements within the scope of the 
present invention, are by way of illustration only, and that various other 
arrangements within the scope of the present invention will occur to those 
skilled in the art upon reading the disclosure set forth herein.

Referring first to FIG. 1, an arrangement is shown where solar cells 2 are 
disposed on the roof 5 of a structure 1, for example a house. Each of the 
cells 2 includes an upper panel 6 and downwardly extending side panels 3E 
and 3W where it will be understood that panel 3E has an easterly exposure 
while panels 3W have a westerly exposure. 
As shown, cells 2 define an open chamber 7 but can be closed if desired. As 
shown in FIG. 2, panels 6 are disposed at an angle 10 with respect to 
horizontal where angle 10 can be selected so that the plane of panel 6 is 
normal to the noon sun at selected times of the year to provide maximum 
radiation receipt. 
Likewise panels 3E and 3W are disposed at selected angles below horizontal 
depending on design considerations and the selected period during the 
daily solar arc when it is desired that the solar rays strike the panels 
at the most direct angle. 
Each of the panels 3E, 3W and 6 has a fluid flow conduit not shown, which 
can be interconnected as described hereinafter to remove heat from the 
panel where the heat results from inpingement of solar radiant energy on 
the panel and adsorbition of the energy by the panel. 
Typically, such panels include a frame with the coil disposed therein and a 
transparent cover over the frame to admit radiant energy and prevent loss 
of heat by convection. 
As shown in FIG. 3A the dimensions of the panels can be selectively varied 
depending on the application and desired performance. 
In FIG. 3A panels 6 have a width 8 which can be in a selected ratio to the 
width 9 which is the horizontal projection of the width of panels 3E and 
3W so that the relative quantities of heat received by the panels can be 
selected. 
For example and referring to FIGS. 3A-3E, FIG. 3A represents early morning 
where solar rays 11 are at a relatively low angle relative to horizontal 
and strike panels 3E and 6 but not directly on panels 3W. It will be 
recognized that at certain angles of incidence of panels 3E and 3W portion 
of the incident radiant energy is reflected from the surface of the panel 
to the next adjacent panel to provide reflected energy to be received by 
the panel. The example shown in FIG. 3B, represents incidence of rays 12 
at a later period when some radiation is received by panels 3W but the 
most direct radiation is received by panels 3E. In the circumstances shown 
in FIG. 3B, and in the absence of other modifying circumstances, it would 
be expected that the temperature of panels 3E would be the greatest 
followed by panels 6 and 3W. If the heat transfer medium were passed in 
fixed series through panels 3E, 6 and 3W the outlet temperature would be 
the weighted average. If the order of flow were 6, 3E then 3W it is 
possible that the heated fluid from panel 3E might actually lose heat in 
panel 3W. 
In accordance with one feature of the present invention the heat transfer 
fluid would flow in the panels in the order 3W, 6, 3E. Thus some heat 
would be recovered from panel 3W and by emitting the fluid through panel 
3E the maximum available .DELTA.T is realized at the time shown. 
FIG. 3C is an illustration of the systems at about solar noon where the 
solar rays 13 impinge directly on panels 6 and at an angle on panels 3W 
and 3E. Likewise FIG. 3D illustrates the incidence of early afternoon rays 
14 on the panels while FIG. 3E illustrates the incidence of late afternoon 
rays 16 on the panels. 
From the foregoing it can be seen that by proper orientation of the panels 
3E, 6 and 3W and by controlling the sequence of flow of the heat transfer 
media through the panels, the heat recovery and final temperatures of the 
fluid can be maximized. Maximization of the outlet temperature is 
particularly important in arrangements where the heat is to be stored 
because the .DELTA.T between the fluid and the storage facility is the 
primary determinant of the quantity of heat available for storage. 
FIGS. 4A-4C shows a cross sectional view of an example of panel arrangement 
where a semi-cylindrical transparent cover 21 is provided to receive 3 
parabolic reflectors 22-24 where coils 26-28 are located at the focus of 
the reflector to receive radiation from the reflectors. Rays 25 are 
provided in FIGS. 4A-4C to illustrate the relative radiation available to 
the reflectors 12-14 at early morning noon and late afternoon as 
previously discussed with respect to FIGS. 3A-3E. 
Referring now to FIG. 5, a schematic diagram of one controlled flow 
arrangement within the scope of the present invention is shown, where 
three heat transfer devices, A, B and C for example as previously 
described where the devices are oriented with respect to incident sunlight 
so that the devices are heated to different temperature relationships 
during a typical day. Each of the heat transfer devices A-C is, 
respectively provided with a heat transfer fluid inlet 54-56 to, for 
example a coil 51-53 respectively to receive heat and transfer a portion 
of the heat to the fluid flowing in coils 51-53. Likewise each heat 
transfer devices A-C is provided with a heat transfer fluid outlet 57-59 
for emission of heat transfer fluid. 
Temperature sensors 61-63 are provided in each of the heat transfer devices 
A-C to measure the effective heat transfer temperature I-III respectively 
available at each heat transfer device as an indication of the maximum 
available heat transfer fluid outlet temperature. The location of the 
temperature sensors depends upon the characteristics of the heat source 
but can be located to provide the most effective measure of the 
temperature available at the heat source. 
It will be understood that, within the scope of the present invention two 
or more heat transfer devices at different temperatures can be utilized 
but in the example shown, three are provided. Likewise numerous flow 
devices and assemblies can be provided within the scope of the present 
invention to conduct a heat transfer fluid first through the coolest heat 
transfer device serially to the warmest. However in the example shown, the 
objectives are accomplished by the use of two way valves. First, three 
solenoid operated normally closed valves NC1-NC3 are provided, in each 
inlet line, 54-56 respectively to each heat transfer device A-C. Each 
valve NC1-NC3 is provided with a solenoid coil 66-68 having one grounded 
terminal G and one power terminal 69-71 respectively, and each valve 
NC1-NC3 also communicates with outlet 45 from a pump 46 which is provided 
to circulate heat transfer fluid, for example brine through heat transfer 
devices A-C as described herein to warm the heat transfer fluid and 
through a coil 42 located in a reservoir 41 where the heat is transfered 
from the heat transfer fluid to, for example fluid 44 stored in reservior 
41 for subsequent recovery of heat in other applications such as, for 
example, space heating. It will be recognized that such heat transfer to 
the fluid 44 occurs only if the temperature of the heat transfer fluid in 
coil 42 is in excess of the temperature of fluid 44 and that the rate of 
heat transfer and therefore the effective recovery of useable heat is 
likewise a function of the temperature difference. 
Each outlet 57-59 of each heat transfer device A-C is provided with a two 
way valve 2x1, 2x3, 2x5 which selectively communicates with a second two 
way valve 2x2, 2x4, 2x6 by means of conduits 72-74 respectively, and with 
an exhaust manifold 73, by means of conduits 106-108, which supplies heat 
transfer fluid to coil 42 as described hereinafter. Each of the valves 
2x1-2x6 is solenoid operated by a core coil 76-81 with a grounded terminal 
G and a power terminal 82-87. 
Two way valves 2x2, 2x4, 2x6 communicate with the associated two way valves 
2x1, 2x3, 2x5 to selectively supply heat transfer fluid to the two heat 
transfer devices with which they are not associated. For example valves 
2x1 and 2x2 are associated with heat transfer device A and valve 2x2 
communicate with heat exchange devices B and C by means of conduits 91 and 
92 respectively. Likewise valve 2x4 communicates with valve 2x3 at the 
outlet of heat transfer device B and with inlets of heat transfer devices 
A and C by means of conduits 93 and 94. Additionally, valve 2x6 
communicates with valve 2x5 at the outlet of heat transfer device C and 
with the inlets to heat transfer devices A and B by means of conduits 96 
and 97. 
The valves NC1-NC3 and 2x1-2x6 can, as shown, be solenoid operated to be 
programmed, for example as shown herein, to direct flow of heat transfer 
fluid through heat transfer devices A-C to provide a maximum temperature 
at the outlet of the warmest heat transfer device. 
As shown, the temperature I-III are supplied to control devices 64-66 to 
control direction and order of flow of heat transfer fluid through heat 
transfer devices A-C as described hereinafter. 
While various means can be utilized to direct the order of flow of heat 
transfer fluid through heat transfer devices A-C, including manual 
control, the objectives of the present invention can be accomplished by 
various means, for example through means shown in FIG. 6. 
In FIG. 6, an arrangement is shown where 3 comparators 101-103 for example 
a National SemiConductor LM-106, are shown, each having two inputs for 
comparison of input signals. The input signals are provided by the outputs 
I-III provided by temperature sensors 61-63 where the sensors may directly 
provide, or may be modified by means not shown but known in the art to 
provide, an electrical signal I-III directly proportional or indicative of 
the temperature and/or maximum heat transfer fluid temperature available 
in the heat transfer devices A-C. 
In the example shown, comparators 101-103 are provided to convert the 
analog signals I-III to provide binary signals designated to binary signs 
0 and 1 at the outputs X, Y and Z of comparators 101-103 depending on the 
relative value of inputs I-III and the characteristics of comparators 
101-103. For example considering comparator 101 and assuming that the 
signals I-III provide higher voltage for higher temperature and lower 
voltage for lower temperatures, and that the temperature available from 
heat exchange device A is lower than available from heat exchange device B 
so it will be assumed that the signal II is higher than the signal I. It 
will also be assumed that the temperature of heat transfer device C is 
greater than the temperatures of heat transfer devices A and B so that the 
voltages of signal III is higher than I and II. 
At comparator 101 signal II is connected to the terminal designated (-) 
while the lower signal I is converted to the (+) terminal. Briefly stated, 
the negative input is greater than the positive input so the signal at X 
is low or 0. Conversely where signal I is greater in magnitude than signal 
II the output X goes high, or 1. 
Each comparator 101-103 thus provides a binary output signal dependant upon 
the relationship of the inputs, and the outputs X, Y and Z provide a 
binary number indicative of the totality of the relationships between the 
signals I II III. The relationship can be shown in summarized form in 
Table I, where the maximum heat effective transfer fluid temperatures at 
the heat sources A, B and C are shown as L, M and H, indicating lowest, 
middle and highest. Likewise, the outputs X, Y and Z of the comparators 
101, 102 and 103 are shown in binary forms for modes a-f at different 
relative temperatures in the heat sources with the base 10 number shown to 
further illustrate the distinctiveness of the particular situation. 
TABLE I 
__________________________________________________________________________ 
ILLUSTRATION OF BINARY GENERATION OF COMATOR OUTPUT 
RELATIVE DEVICE 
HEAT TRANSFER DECIMAL BASE 
FLOW 
MODE DEVICE TEMPERATURE 
COMATOR OUTPUT 
EQUIVALENT 
ORDER 
A B C X Y Z 
__________________________________________________________________________ 
a L M H 0 0 0 0 A-B-C 
b L H M 0 0 1 1 A-C-B 
c M H L 0 1 1 3 C-A-B 
d M L H 1 0 0 4 B-A-C 
e H L M 1 0 1 5 B-C-A 
f H M L 1 1 1 7 C-B-A 
__________________________________________________________________________ 
As shown in FIG. 5 the binary inputs X,Y and Z are provided to a latch 65 
for example a Motorola MC14174B hex type D flip-flop which is selectively 
and periodically actuated by pulses from clock 105 to transfer the binary 
input X,Y, and Z to a device to convert the code to useful means for 
example, a binary coded decimal to 6 segment decoder 107, hereinafter 
referred to as BCD decoder 107. BCD decoder 107 provides 6 outputs a-f 
each corresponding to modes a-f each actuated in response to one of the 
comparator binary output combinations a-f shown in Table I so that for any 
of the Modes a-f shown in Table I one of the outputs a-f is actuated. 
In the example within the scope of the present invention shown in FIG. 6, 
each output a-f is utilized as an actuator for preprogrammed relay 107-112 
when each preprogrammed relay is supplied with a source of power, not 
shown, and each preprogrammed relay 107-112 is adapted to selectively 
provide power to selected terminals 69-71, 82-87 of relays 66-68, 76-81 of 
valves NC1-NC3 and 2x1-2x6 respectively so that each preprogrammed relay 
107-112 actuates each valve combination differently to provide selected 
flow patterns through heat transfer devices A-C depending on the 
temperature relationship of the heat transfer devices. 
It has been found that arrangements within the scope of the present 
invention can include any number of heat transfer devices and that where 
binary system control systems is utilized the number of comparators 
required to equal to: 
##EQU1## 
where n=the total number of heat transfer devices. 
The optimum control sequences corresponding to the modes shown in FIG. 5 is 
shown in Table II where the modes shown in Table I are reflected as the 
direction of fluid flow in valves NC1-NC2 and 2x1-2x6. 
TABLE II 
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VALVE SETTINGS 
MODE 
NC1 NC2 
NC3 2 .times. 1 
2 .times. 2 
2 .times. 3 
2 .times. 4 
2 .times. 5 
2 .times. 6 
OPEN TO 
__________________________________________________________________________ 
a O* C* C 2 .times. 2 
B(in)* 
2 .times. 4 
C(in) 
Ex -- 
b O C C 2 .times. 2 
C(in) 
Ex -- 2 .times. 6 
B(in) 
c C C O 2 .times. 2 
B(in) 
Ex -- 2 .times. 6 
A(in) 
d C O C 2 .times. 2 
C(in) 
2 .times. 4 
A(in) 
Ex -- 
e C O C Ex* -- 2 .times. 4 
C(in) 
2 .times. 6 
A(in) 
f C C O Ex -- 2 .times. 4 
A(in) 
2 .times. 6 
B(in) 
__________________________________________________________________________ 
Ex = Exhaust Conduit 73 
(in) = inlet to Heat Transfer devices A, B and C. 
C = Closed 
O = Opened 
By the foregoing means, the flow order of heat transfer fluid through the 
device can be selected to provide maximum output temperature in the heat 
transfer fluid. 
It will be understood that the foregoing is but one example of an 
arrangement within the scope of the present invention and that various 
other arrangements and devices within the scope of the present invention 
will occur to those skilled in the art upon reading the disclosure set 
forth hereinbefore.