Development of a Low-Cost Soil Heat Flux and Temperature Profile with Logger
Loading...
Date
2019-07-26
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
International Journal of Advances in Scientific Research and Engineering
Abstract
Variation of soil temperature and soil heat flux measurements from a locally fabricated and calibrated device were analyzed and
compared with a standard device. The soil heat flux consists of two-disc aluminum plates, dielectric material and two
thermocouples such that each thermocouple was sandwiched between the aluminum plates and one side of the dielectric material.
The sizes of the aluminum plates and the dielectric material were 32 mm in diameter and their thickness is 2.5 mm. Differential
temperature between two thermocouples attached to two aluminum plates separated by a thermal insulator was used to measure
the soil heat flux values. The thermocouples amplifier module AD8495 and then combined with a 16-bit Analog to Digital
Converter (ADS1115) for a good measurement resolution was employed for the signal conditioning. A semiconductor sensor
DS18B20 was used to measure the soil temperature. The microSD shield was included for storing data and DS3232, a Real Time
Clock (RTC) module for timekeeping. Arduino mega 2560 microcontroller was used to coordinate the whole active and display
the activities on LCD. The soil heat flux sensor was calibrated using the principle of thermal conduction over the surface area by
heating with a known heat source. The thermal conductivity of heat flux is given by 3.3407 (WV-1m-1) from the empirical
deduction. The temperature sensing unit was checked for accuracy by inserting it inside a calorimeter with the mercury-in-glass
thermometer and the correlation obtained was 0.92. The soil heat flux and temperature sensing unit were compared with that of
standard Campbell device. The correlation obtained for soil heat flux and temperature were 0.89 and 0.95 respectively. The result
obtained when installed at the Redeemer’s University, Ede, Nigeria, the variation of soil heat flux and temperature when placed at
the same level of 10 cm into the soil gave the same value. The maximum peak of heat flux density usually occurs at about 13:00
pm to 15:00 pm with values around 260 W/m2 at 10 cm. The logging interval can be preset to any rate from 30 seconds and
above.
Description
Keywords
Soil Heat Flux, Temperature, Thermocouple, Aluminum Plate, Dielectric Material