A Device to Register Temperature in Boreholes in Northwest Spain for Geothermal Research
Abstract
:1. Introduction
- To design a thermal energy storage equipment and ground heat exchangers. Ref. [24] used long-term ground temperature records from 20 sample sites scattered throughout five states of Australia.
- -
- At 5 m deep, the amplitude of the temperature wave is 1.66 °C;
- -
- At 10 m, the amplitude drops to 0.72 °C.
2. Background
- Systems with probes that move inside a borehole suspended by a cable (wired probe)
- Systems with probes that move inside a borehole without cable (non-wired probes)
- Systems with sensors permanently located in the borehole
- Systems with sensors combined with other elements of the borehole
- ○
- Commercial sensors were installed over geothermal pipes, and were embedded in the geothermal grout and connected to the data logger with a wire;
- ○
- The DS18B20 sensors were connected with a one-wire cable which supplies energy to the sensor and transmits a signal to a specifically designed data logger, placed outside the borehole. This is a novel and simple setting, which has proven to be useful as temperature data are registered for a long period of time.
3. Materials and Methods
3.1. Boreholes and Geothermal Instrumentation
3.1.1. Boreholes Q-Thermie-Uniovi 1 and 2
Geothermal Borehole “Q-Thermie-Uniovi-1”
- Easy to assemble: a coaxial geothermal pipe is easier to insert compared to the U-shape pipe. On the one hand, for U-shape pipes, several pipes must be lowered simultaneously, which are joined with an “elbow” at the bottom of the borehole, where a counterweight is also located to facilitate the descent. The coaxial pipes are descended using the following steps: firstly, a unique pipe is inserted—in this case, the outer tube (close at the bottom); secondly, the inner pipe is easily introduced as the outer tube protects it. On the other hand, the use of a head as a linking element between the geothermal pipes and the outside installation of the borehole simplifies the connections outside the borehole.
- Usage flexibility: various configurations can be used—for example, the inner pipe can be removed and changed, or new instrumentation can be inserted.
- Space availability and accessibility for the instrumentation: the installation of temperature sensors in the space between the outer pipe and the borehole walls can be measured, which descends easily at the same time as the outer pipe.
- Commercial TMCX-HD temperature sensors placed on the external wall of the outer geothermal tube;
- Commercial DS18B20 temperature sensors placed on the external wall of the outer geothermal tube.
Geothermal Borehole “Q-Thermie-Uniovi-2”
- A commercial TMCX-HD temperature sensor placed on the exterior the geothermal tube;
- A commercial DS18B20 temperature sensor hung into the geothermal tube from bus 1-wire.
3.2. Temperature Sensors and Its Connection
3.2.1. TMCx-HD Sensors
- Dimensions:;
- Weight: ;
- Measurement range: to in water/soil;
- Measurement range: to in air;
- Response time in air: typical to in air moving ;
- Accuracy with HOBO U-12: . from to ;
- Resolution with HOBO U-12: at ;
- Housing: copper-plated sensor tip.
Connection of the TMCx-HD Sensors to the Data Logger
3.2.2. DS18B20 Sensors
- The unique 1-wire® interface requires only one port pin for communication;
- Measures temperatures from −55 °C to +125 °C (−67 °F to +257 °F);
- Measures ± 0.5 °C accuracy from −10 °C to +85 °C;
- Measures programmable resolution from 9 bits to 12 bits;
- No external components are required;
- Parasitic power mode requires only 2 pins for operation (DQ and GND);
- Simplifies distributed temperature-sensing applications with multidrop capability;
- Each device has a unique 64-bit serial code stored in on-board ROM.
Bus 1-Wire: DS18B20 Sensors Connection
3.3. Data Logger Types
3.3.1. HOBO U12-006 Data Logger
- Analog channels: 0 to 2.5 Vdc (w/CABLE-2.5-STEREO), 0 to 5 Vdc (w/CABLE-ADAP5), 0 to 10 Vdc (w/CABLE-ADAP10), and 4–20 mA (w/CABLE-4–20 MA);
- Accuracy (logger only): ±2 mV ± 2.5% of absolute reading and ±2 mV ± 1% of reading for logger-powered sensors;
- Resolution: 0.6 mV;
- Sample rate: 1 s to 18 h, user-selectable;
- Time accuracy: ±1 min per month at 25 °C (77 °F);
- Operating range: −20 to 70 °C (−4 to 158 °F);
- Operating temperature: −20 to 70 °C (−4 to 158 °F) (logging), 0 to 95% (RH (non-condensing));
- Launch/readout: 0 to 50 °C (32 to 122 °F), per USB specification;
- Humidity range: 0 to 95% (RH (non-condensing));
- Battery life: 1-year typical use;
- Memory: 64 Kbytes (43,000 12-bit measurements);
- Weight: 46 g (1.6 oz);
- Dimensions: 58 × 74 × 22 (2.3 × 2.9 × 0.9 ).
3.3.2. Arduino UNO Data Logger
3.4. Individual Calibration of DS18B20 Sensors
3.4.1. General Sensor Calibration
3.4.2. Individual Sensor Calibration
- (1)
- The tube with the 1-wire was introduced into a thermal bath;
- (2)
- The 1-wire was connected to the Arduino UNO, as indicated above, and equipped with the data reading/registering program;
- (3)
- Temperature variations were registered for 5 min and several hours in each sensor. The thermal bath temperature varied, while registering the sensor readings. This defined several calibration zones with different temperatures.
4. Results
4.1. “Q-Thermie-Uniovi-1” Borehole
4.1.1. TMCx Sensors
4.1.2. DS18B20 Sensors
4.1.3. Comparative Study between the Measurements of Both Sensors Located at a Similar Depth and with the Same Ubication in the Pipe
4.2. “Q-Thermie-Uniovi-2” Borehole
4.2.1. TMCx Sensors
4.2.2. DS18B20 Sensors
Temperatures from Sensor S8.23
Temperatures from Sensor S10.31
Calculated Temperatures at 9.5 m
4.2.3. Comparative Results
4.3. Measurements Registered by the Sensors
5. Discussion and Conclusions
- Thermal jumps:
- ○
- The TMCx-HD sensors produce thermal jumps of 0.024 °C;
- ○
- The DS18B20 sensors produce thermal jumps of 0.0625 °C.
- ○
- The thermal jump for the TMCx-HD at 9.5 m is 0.024 °C;
- ○
- The thermal jump for the DS18B20 sensors located at 8.23 and 10.31 m is 0.069 °C and 0.0601 °C, respectively.
- Sensor position:
- ○
- In the “Q-Thermie-uniovi-1” borehole, both types of sensors are at the same depth and the same relative position, i.e., on the outside of the outer geothermal pipe.
- ○
- The TMCx-HD sensors register temperatures of 16.344 °C, while the DS18B20 sensors register temperatures of 16.062 °C, showing a difference 0.282 °C. The 1-wire is not calibrated; hence, the temperatures which should be the same (since they are measured in the same position) are not.
- ○
- In the “Q-Thermie-uniovi-2” borehole, the sensors are in different relative positions. Those of the TMCx-HD type are located on the outer face of the geothermal pipe, embedded in the geothermal fill, while the 1-wire DS18B20 sensors are on the geometric axis of the 50 mm geothermal tube.
Author Contributions
Funding
Institutional Review Board Statement
Informed Consent Statement
Data Availability Statement
Acknowledgments
Conflicts of Interest
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Borehole Depth (m) | |
---|---|
Q-Thermie-Uniovi-1 | Q-Thermie-Uniovi-2 |
1.5 | 1.5 |
4.5 | 4.5 |
9.5 | 9.5 |
Q-Thermie-Uniovi-1 | Q-Thermie-Uniovi-2 | ||
---|---|---|---|
Depth at the Borehole (m) | Distance between Sensors (m) | Depth at the Borehole (m) | Distance between Sensors (m) |
On the surface | On the surface | ||
1.60 | 1.67 | ||
4.00 | 2.36 | 3.86 | 2.19 |
6.08 | 2.22 | ||
8.23 | 2.15 | ||
9.40 | 5.40 | 10.31 | 2.08 |
12.44 | 2.13 | ||
15.02 | 5.62 | 14.55 | 2.11 |
16.72 | 2.17 | ||
18.01 | 1.29 | ||
20.04 | 5.02 | 20.14 | 2.13 |
22.17 | 2.03 | ||
25.02 | 4.98 | 24.22 | 2.05 |
26.26 | 2.04 | ||
28.38 | 2.12 | ||
30.70 | 5.68 | 30.44 | 2.06 |
32.50 | 2.06 | ||
35.80 | 5.10 | 34.61 | 2.10 |
36.75 | 2.15 | ||
38.85 | 2.10 | ||
41.40 | 5.60 | 40.98 | 2.13 |
43.41 | 2.43 | ||
46.50 | 5.10 |
Zone Number | Mean Temperature | Assessment of Zone Temperature |
---|---|---|
Zone 1 | Stable | |
Zone 2 | Stable | |
Zone 3 | Variable | |
Zone 4 | Stable |
Sensor 1.67 m | Sensor 3.86 m | Sensor 6.08 m | Sensor 8.23 m | Sensor 10.31 m | Sensor 12.44 m | Sensor 14.55 m | |
a | 0.995 | 1.0007 | 1.0074 | 0.989 | 1.0074 | 1.004 | 0.999 |
b | 0.042 | 0.1458 | −0.0979 | 0.127 | −0.3203 | −0.008 | −0.054 |
R2 | 0.998 | 0.9985 | 0.9985 | 0.998 | 0.998 | 0.998 | 0.998 |
Sensor 16.72 m | Sensor 18.01 m | Sensor 20.14 m | Sensor 22.17 m | Sensor 24.22 m | Sensor 26.26 m | Sensor 28.38 m | |
a | 0.999 | 0.993 | 0.991 | 0.9996 | 0.992 | 0.994 | 1.004 |
b | 0.1748 | 0.076 | 0.048 | 0.102 | 0.144 | 0.358 | −0.285 |
R2 | 0.995 | 0.994 | 0.997 | 0.998 | 0.996 | 0.998 | 0.997 |
Sensor 30.44 m | Sensor 32.50 m | Sensor 34.61 m | Sensor 36.75 m | Sensor 38.85 m | Sensor 40.98 m | Sensor 43.41 m | |
a | 0.9996 | 0.9984 | 0.998 | 0.9865 | 0.9897 | 0.997 | 1.017 |
b | −0.05 | 0.0023 | 0.1339 | 0.2833 | 0.07 | 0.1167 | −0.3402 |
R2 | 0.998 | 0.998 | 0.9976 | 0.9979 | 0.997 | 0.998 | 0.9965 |
Sensor Type | Depth (m) | Temperature Measured (°C) | Difference (°C) |
---|---|---|---|
TMC | 9.5 | 16.344–16.368 | 0.282 |
DS1820 | 8.23 | 16.062 | |
Potential cause of the temperature difference | Lack of calibration of DS18B20 sensors |
Sensor Type | Depth (m) | Temperature Measured (°C) | Temperature Estimated (°C) |
---|---|---|---|
TMC | 9.5 | 15.939 | |
DS1820 | 8.23 | 16.089–16.011 | |
10.31 | 15.744 | ||
15.906–15.952 | |||
Temperature differences = 0.013–0.033 °C |
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Marcos-Robredo, G.; Rey-Ronco, M.Á.; Castro-García, M.P.; Alonso-Sánchez, T. A Device to Register Temperature in Boreholes in Northwest Spain for Geothermal Research. Sensors 2022, 22, 4945. https://doi.org/10.3390/s22134945
Marcos-Robredo G, Rey-Ronco MÁ, Castro-García MP, Alonso-Sánchez T. A Device to Register Temperature in Boreholes in Northwest Spain for Geothermal Research. Sensors. 2022; 22(13):4945. https://doi.org/10.3390/s22134945
Chicago/Turabian StyleMarcos-Robredo, Germán, Miguel Ángel Rey-Ronco, María Pilar Castro-García, and Teresa Alonso-Sánchez. 2022. "A Device to Register Temperature in Boreholes in Northwest Spain for Geothermal Research" Sensors 22, no. 13: 4945. https://doi.org/10.3390/s22134945