A change in the air temperature inside a 20-liter chamber when air is added from the receiver

Introduction. One of the reasons for the overestimation of the explosion hazard of dust inside a (20 ± 2)-liter chamber is the elevated initial temperature of the air suspension. The initial temperature is also raised by the process of filling the pre-emptied chamber with air from the receiver, used to distribute dust over the chamber. In this work, an increase in the air temperature inside an 18.7-liter chamber was identified in an experiment for the case of addition of air from the receiver.The methodology of an experiment. The air temperature in the chamber was measured at the time when the air from the receiver was added using a WR 5/20 thermoelectric converter (a thermocouple). The thermocouple junction was located at the distance of 70 mm from the inner wall of the chamber. The thermocouple signal was processed by an MCLab PRO programmable logic controller (the time resolution is 1 ms).Research results. The measuring instruments recorded an increase in the temperature of the thermocouple junction by +14 degrees. Due to the comparability of the inertia of the thermocouple (3 s) and the characteristic time of air cooling by the chamber walls (5 s), the measurement results underestimated the real value of a jump in the air temperature inside the chamber. Measurement results were refined using a simple model of heat transfer between the objects involved in the process (thermocouple junction – air – chamber wall) that entailed the exponential relaxation of the temperature difference over time. As a result, an estimated increase in the initial temperature inside the chamber of +30 degrees was identified.Results and discussion. The temperature jump by +30 degrees makes a noticeable contribution to the total jump in the initial temperature, which was previously tied solely to the burnout of the ignition source (+80 degrees).Conclusions. Given the known increase in the temperature inside the chamber caused by the burnout ofa standard ignition source (2 kJ), the real value of the initial temperature of the environment can reach 135 °C in the course of studying dust in a (20 ± 2)-liter chamber.

Efek Bentonit pada Karakteristik Pembakaran Droplet Biodiesel Kelapa Sawit

The blends of fuel to base liquid fuels for the enhancement of combustion properties has long generated interest since it is linked to improvement in combustion properties in biodiesel fuels. This work investigates the effect of bentonite nanoparticles on the combustion characteristics of palm oil biodiesel. These nanoparticles are added in various compositions on biodiesel which are 0% (B0), 10% (B10), 20% (B20) and 30% (B30). The insulin pen was used to make Sub-millimeter-sized spherical droplets, and the combustion process of droplets was recorded using a camera in atmosphere condition. The fuel was dripped on the tip of the thermocouple junction and ignited using a torch of the butane-air mixture on a cylindrical burner. Properties such as ignition delay, burning rate, and flame temperature of droplets were measured with post-processing of the resulting images. The results showed a decrease in ignition delay and an increase of flame temperature with the increase of bentonite percentage due to bentonite acts as a catalyst capable of accelerating the reaction rate. However, the burning rate decrease with the increasing of bentonite percentage due to the oxygen content of the mixture is getting lower.

Dynamic Error Correction of Filament Thermocouples with Different Structures of Junction based on Inverse Filtering Method

Since filament thermocouple is limited by its junction structure and dynamic characteristics, the actual heat conduction process cannot be reproduced during the transient thermal shock. In order to solve this problem, we established a thermocouple dynamic calibration system with laser pulse as excitation source to transform the problem of the restoring excitation source acting on the surface temperature of thermocouple junction into the problem of solving the one-dimensional (1D) inverse heat conduction process, proposed a two-layer domain filtering kernel regularization method for double conductors of thermocouple, analyzed the factors causing unstable two-layer domain solution, and solved the regular solution of two-layer domain by the filtering kernel regularization strategy. By laser narrow pulse calibration experiment, we obtained experimental samples of filament thermocouples with two kinds of junction structures, butt-welded and ball-welded; established error estimation criterion; and obtained the optimal filtering kernel parameters by the proposed regularization strategy, respectively. The regular solutions solved for different thermocouples were very close to the exact solution under the optimal strategy, indicating that the proposed regularization method can effectively approach the actual surface temperature of the thermocouple junction.

Low temperature combustion of organic coal-water fuel droplets containing petrochemicals while soaring in a combustion chamber model

The paper examines the integral characteristics (minimum temperature, ignition delay times) of stable combustion initiation of organic coal-water fuel droplets (initial radius is 0.3-1.5 mm) in the oxidizer flow (the temperature and velocity varied in ranges 500-900 K, 0.5-3 m/s). The main components of organic coal-water fuel were: brown coal particles, filter-cakes obtained in coal processing, waste engine, and turbine oils. The different modes of soaring and ignition of organic coal-water fuel have been established. The conditions have been set under which it is possible to implement the sustainable soaring and ignition of organic coal-water fuel droplets. We have compared the ignition characteristics with those defined in the traditional approach (based on placing the droplets on a low-inertia thermocouple junction into the combustion chamber). The paper shows the scale of the influence of heat sink over the thermocouple junction on ignition inertia. An original technique for releasing organic coal-water fuel droplets to the combustion chamber was proposed and tested. The limitations of this technique and the prospects of experimental results for the optimization of energy equipment operation were also formulated.

Predictive Modelling of the Warming up Times for Thermoelectric Converters

In the present article the question of simulation of nonstationary process of heat transport in a sensitive element of the thermoelectric transformer with an uninsulated seal is considered. The model allows defining and comparing the heating time of a thermocouple junction up to the given temperature for different types of thermocouples. In this article the values obtained by means of modelling the heat time of different thermocouples and also a temperature field in a sensitive element of the thermoelectric transformer are given.

Considerations Regarding the Measuring the Performance of a Vehicle during Braking on a Slope Extended

In this paper we present some aspects regarding the measurement of the effects of extended of braking, or the overheating of the braking system of a vehicle driving downhill with continuous or intermittent operation of the braking system. One of the is the extended effects of high temperature of braking brake blocks. To determine their temperature were used thermocouple temperature sensors. To determine temperature friction lining unshielded thermocouple junction was used to reduce the thermal inertia of 1 ÷ 2 [, thus ensuring the greater accuracy of measurement data. To determine the metal part of the brake shoe to temperature using a thermocouple sensor with metal sheathed.

Comparison of Piston Temperature Measurement Methods: Templugs Versus Wireless Telemetry With Thermocouples

The objective of this investigation was to compare the results of metallurgical temperature sensors and thermocouples when used to measure piston temperatures in a running engine. Type J thermocouples and a microwave wireless telemetry system were used to gather real time temperature data on the piston in the vicinity of each metallurgical sensor. Eight pairs of metallurgical temperature sensors were installed in the piston with a thermocouple junction in-between. The engine was ramped up to steady state quickly and then held for approximately 4 h at 1800 rpm and 1980 Nm before being quickly ramped back down in accordance with the metallurgical sensors' recommended test cycle. During the test, continuous temperature data at each of the sensor locations were monitored and recorded using the telemetry system. After the test was complete, the metallurgical temperature sensors were removed and independently analyzed. The results indicate that readings from the metallurgical temperature sensors were similar to those of the embedded thermocouples for locations without large thermal gradients. However, when thermal gradients were present, the metallurgical sensor's reading was influenced measurably.