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This paper presents technologies and experiments of a wireless sensors using two thermocouples network. It was established that the energy consumption during sensor measurements is usually up to 10 times lower compared to the energy consumption at the time of establishing wireless connection for most protocols. For this reason, new simplified wireless connection protocol was created. Extremely low energy wireless sensor hardware and software equipment was designed. The newly created universal measurement module allows the use not only thermocouples, but also various types of analogue sensors, thermocouples, pressure bridges, Resistance Temperature Detectors (RTD) and digital sensors communicating through SPI or I2C interface. The newly designed specific power supply scheme allows to supply the sensor and radio module with the voltage from 1.2 V to 3.6 V batteries. When conducting periodic measurements every second, the use of newly designed hardware and software equipment enables the wireless sensor to be operated for up to 3 years from two 1200 mAh capacity batteries.

The production of thermal energy is one of the sources of environmental pollution, especially when it uses traditional fossil fuels (in particular hard and brown coal). Burning conventional fuels contributes to air pollution because of emitting gases and producing waste after the process of burning in the form of ash. The work below was aimed at determining the indirect emission of PAHs in the form of fly ash, depending on the type of fuel burned. The conducted research showed which solid fuel combustion content leaves the lowest content of PAH in the fly ash. This work contains the analysis and assessment of the content of 16 PAHs (polycyclic aromatic hydrocarbons) in fly ash from the combustion of five selected solid fuels in low-power boilers. The following fuels were chosen for the research: hard coal with granulation above 60 mm, coal with the grain size of 25–80 mm, coal with the grain size of 8–25 mm, pellets with the grain size of 6 mm, and mixed dry wood. The results of the research showed that the most frequent and most concentrated compounds were naphthalene and acenaphthylene from the PAH group. These hydrocarbons have the smallest number of rings in a molecule. It was also found that the content of the LMW (Low Molecular Weight Polycyclic Aromatic Hydrocarbons) fractions in the fly ash from the analyzed fuels in ∑PAHs exceeds 57% in the case of 6 mm pellets and in the case of the ash from wood and hard coal when the grain size >60 mm. The opposite dependence can be observed in the case of the HMW (High Molecular Weight Polycyclic Aromatic Hydrocarbons) fraction.

In this paper some interesting and novel features of a four-terminal (4T) network are presented. A single DC current source (J) is switched over and connected in turns to opposite arms of the four-element bridge circuit. This twooutput circuit with two voltage outputs is called a double current circuit (2x1J). The output voltages are differently dependent on the arm resistance increments and their values are given in absolute and relative units. An original application with two sensors acting as strain gauges and RTD's is presented. Signal conditioning formulas of 2D measurement of deflection and temperature of a cantilever beam are discussed in detail. Some results achieved with the use of the circuit are presented, as well.