Tesis
Instrumentação para levantamento de dados do perfil geotérmico superficial visando a troca sustentável de calor
Fecha
2014-10-10Registro en:
LONGO, Adriano José. Instrumentation to obtain the data profile of surface
geothermal heat aiming at sustainable heat exchange. 2014. 97 f. Dissertação (Mestrado em Engenharia Elétrica) - Universidade Federal de Santa Maria, Santa Maria, 2014.
Autor
Longo, Adriano José
Institución
Resumen
Nowadays, the rational energy consumption is one of the main concerns of the whole
modern society. Thus, this dissertation contributes to improve energy efficiency, increase the
renewable energy sources and to develop cleaner and more efficient technologies as the
greatest challenges of science and technology. This is reflected in today s residential energy
consumption in Brazil which is about 26%, mostly produced by equipment of high energy
consumption as is the case of showers and air-conditioning, according to the Energy Research
Company - EPE. The main goal of this research was to develop a dedicated electronic
instrumentation to determine the superficial geothermal profile, focusing at cost reduction and
short installation times. With many experimental data was possible to establish the heat
exchange capacity of heat exchangers buried underground. The experimental data was
obtained in the Center of Studies in Energy and Power Systems Center (CEESP) at Federal
University of Santa Maria (UFSM). It was developed a dedicated acquisition board based on a
microprocessor (PIC18f5420) and a tubular PVC probe setup with 11 digital temperature
sensors model DS18B20 with 5 m long rod and half inch diameter. The temperature data were
collected during 12 months recorded every 2 minutes This dissertation is mostly focused on the establishment of basic electronic
instrumentation for conducting summary surveys of temperature data in shallow subsurface
geothermal profile in any area, thereby reducing costs and installation times. These
geothermal profile data are important for various areas in establishing the ability to exchange
heat between buried materials and the homely ambient, such as construction, underground
power cabling and architecture. The experimental area was the Center of Studies in Energy
and Power Systems (CEESP), in the campus of UFSM in Santa Maria - RS. The data
collection will serve as input for the rapid establishment of underground temperature
distribution curves where is intended to utilize geothermal energy. The data collection was
realized by a dedicated data logger based on the PIC18f5420 microprocessor. The entire plate
is sized, constructed and programmed in CEESP along with a standard PVC tubular probe
five meters long and half inch diameter fitted with 11 digital temperature sensors type
DS18B20, to enable monitoring the underground temperature change from surface up to a
desired depth.
Collection of temperature data was made in the course of 12 months, with
measurements recorded at every 2 minutes. Some interruptions occurred during the
measurement period, but it did not interfere with the final outcome results. It was then
possible to establish the mean thermal profile parameters during daily periods and the
maximum and minimum temperatures throughout the year.
With the results obtained in this research is possible to prove that the thermal variation
(temperature) of the soil profile decreases gradually with depth until it stabilizes at a value
which is approximately the average annual temperature of that local area. During these tests,
it was observed that the temperature measurements in the experimental campus CEESP for a
maximum depth of five meters ranged between 18 and 22 °C. The data reduction method
called Least Squares Method was used to make projections of temperatures for deeper depths.
Thus it was possible to confirm the theoretical information that the soil temperature at any
location a few meters deep tends to stabilize at the annual average surface temperature in that
place. In Santa Maria-RS, according to the National Institute of Meteorology (INMET), the
annual average temperature is 19.5 °C.