1. Jacob Arend, Leon Guan, Matthew Monroe, Taylor Rupp, D’Anne Wilder, David Yu, Juan Gilardo Texas A&M University
Abstract
Method
New Design
Block Diagram
System Sketch
Testing
This project entailed enhancing the design of a “Small-scale
Concentrating Solar Thermal System” to heat water with maximum efficiency.
To verify that the new design was more efficient due to minimizing elements
of heat loss, a test was conducted to find the heat transfer of the copper heat
pipe (used in the original design) to an aluminum cylindrical block. A
stagnation test was then performed to test the efficiency of the new design,
which proved to be 19.057% efficient. The new design appeared to be more
efficient, but has much room to be further improved to reach maximum
efficiency.
Evacuated Tube
Water
Tank
Fresnel Lens
Sunlight
Flow Meter
The new design has water entering the evacuated tube through a
copper pipe (at the top inlet) and exiting the system through an output pipe
(at the right outlet) after being heated. The design provides more efficient
heat transfer by decreasing free convection and increasing forced
convection. This is done by having the water flow directly through the
evacuated tube. In addition, by eliminating the copper heat pipe, the
design reduces the radiation resistance and overall loss of the system.
Stagnation Test
(No Water Flow)
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Temperature Change
Temperature Change
Linear (Temperature Change)
Dynamic Test
(With Water Flow)
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Irradiance
Irradiance
𝐸𝑠𝑡𝑜𝑟𝑒𝑑 = 𝑚𝑐∆𝑇
= (200 𝑔) 4.186
𝐽
𝑔 ∗ ° 𝐶
(5° 𝐶)
= 4186 𝐽
𝐴 𝑒 = 𝜋𝑟𝑙 = 0.01178 𝑚2
𝐸𝑖𝑛 = 𝐴 𝑒 𝐼 𝑑𝑡 = 21456 𝐽
𝑡
0
𝜂 =
𝐸𝑠𝑡𝑜𝑟𝑒𝑑
𝐸𝑖𝑛
= 19.507 %
This monitoring system allows us to store information about
different factors that determine what is going on at any time at the
Concentrator. The system monitors temperature at different important
locations; it also reads input solar irradiance from a pyranometer and
flow of current of the water system. All of this information is displayed
at all times on a LCD screen attached to the Arduino controller and
ready to be extracted through the SD card plugged to the monitoring
system. All of the information is dated and recorded on a text file
indicating the readings from each sensor.
Initial Design
To maximize heat transfer of the water,
several aspects needed to be tested to
improve the original design. Originally,
the design had a copper heat pipe
inserted from the center of the
evacuated tube to a water header,
which the water ran through, to transfer
the heat as shown below in Figure 1.
This design was rejected because too
much heat would be lost due to free
convection and conduction, so a new
design was implemented.
Due to many problems,
the dynamic test could
not be properly
performed. Before any
data could be recorded,
the evacuated tube burst
due to the water being
too cool for the quickly
heated glass under the
fresnel lens.