Computing Concentration Distribution of Lump Additives in Argon-stirred Melt

To modify easily chemical consistence of molten steel metallurgical plants usually add alloys in a form of lumps through a hopper at ladle`s top. The problem is a large variety of adjusted technological conditions for this process, which leads to iterative discovery of rational ones. The article presents synthesis of a mathematical model for the mentioned process using Navier-Stokes and Euler-Lagrange equations. It is designed for researching of process modes depending on: a horizontal position of addition hopper relatively to argon plug at ladle bottom, an average diameter of spherical addition lumps, a total mass of addition heap, a necessity of the second hopper, a temperature of the melt. It takes into account interconnected three-dimensional fluid and solids dynamics, temperature exchange between melt and lump, also it computes level of concentration homogenization. A numerical experiment shows a significantly better addition homogenization when two hoppers are simultaneously used for a feeding. Adequacy checks are performed using ice balls in air-stirred water.

The Effect of Supply and Outdoor Air Temperature on The Enthalpy and Temperature Exchange Efficiency of a Paper Heat Exchanger

Heat Recovery Ventilator (VHR) is widely used nowadays as it is capable to maintain high Indoor Air Quality (IAQ) while minimizing the energy loss of indoor air through air-to-air heat exchanger principle. The main component that enables VHR to perform air-to-air heat exchange is known as Paper Heat Exchanger (PP-HEX). Hence, the objective of this research is to study and analyse the performance of a PP-HEX under different return and outdoor air temperatures as well as their effect on both enthalpy and temperature exchange efficiency. Moreover, some numerical models of VHR have been developed to optimize some complex cases and the numerical models are meant to reduce the physical experiments to analyze or improve complex cases in the future. To the best of the authors knowledge, there is no experimental data available from any sources to validate the numerical models. To address this issue, two different supplies of PP-HEX are tested with an actual VHR, and both PP-HEXs will be referred to as PP-HEX-A and PP-HEX-B due to confidentiality. Furthermore, the testing is conducted in a temperature-controlled testing laboratory and the testing conditions are set according to the ISO standard. The preliminary testing results show that the temperature exchange efficiency and enthalpy exchange efficiency of the PP-HEXs have the same trends while the outdoor air temperature is fixed and varying the temperature of indoor air. In contrary, the temperature exchange efficiency and enthalpy exchange efficiency of the PP-HEXs have the same trends while the indoor air temperature is fixed and varying the temperature of outdoor air as well. With the default voltage supplies (240V) to VHR and the setup conditions (according to the ISO Standard) of return air to be 27°C and outdoor air to be 35°C, the testing results show that PP-HEX-A has a temperature exchange efficiency and enthalpy exchange efficiency with a range of (37.97 – 40.28) % and (30.77 – 57.81) % respectively. While PP-HEX-B has a temperature exchange efficiency and enthalpy exchange efficiency with a range of (35.29 – 42.5) % and (39.6 – 55.93) % respectively.

Water regeneration as an economical advantage of contemporary pasteurizing machines

The problem of preserving food and increasing their biological stability is one of the important problems of modern food production. The pasteurization process, due to the transition to a temperature of up to 60-70 degrees, remains unchanged preservation of liquid products. The considered system of the tunnel pasteurization process, which is used in the production of beer and other fermentation beverages, makes it possible to increase the energy efficiency of the pasteurization process due to the reuse of heated water and temperature exchange between the chambers of the system and product cooling. Reducing energy consumption for heating by using such an automated system can be up to five times. In addition, the use of this system leads to significant savings in water consumption.

Effect of Supply and Exhaust Air Velocity on the Enthalpy and Temperature Exchange Efficiency of a Paper Heat Exchanger

Heat Recovery Ventilators (HRV) are gradually becoming more popular in urban cities and buildings as it is able to effectively maintain the indoor air quality while also using minimal amounts of energy. The key component in the HRV is the Paper Heat Exchanger, which allows the heat exchange of indoor and outdoor air through a crossflow, while also filtering out stale air and dust particles. This article investigates the effect of manipulating the supply and exhaust air velocity on the enthalpy and temperature exchange efficiency of a paper heat exchanger. Data is obtained from experimental results, where the experiments are conducted in a test lab using heat recovery ventilators (HRV) installed with paper heat exchangers. Two paper heat exchangers from different suppliers were tested inside a HRV installed in an air conditioned room. The HRV fan speed was varied at a fixed interval of 0.5 m/s, and the air velocity was measured by using a wind speed meter. At the same time, a USB data logger was used to collect relative humidity and temperature of the air at the supply inlet, indoor air inlet, and return air outlet to determine temperature exchange efficiency and the enthalpy of air. The results of the testing shows that the HRV was able to achieve a temperature exchange efficiency of 47 to 63% and enthalpy exchange efficiency of 63 to 94% for PHEX-A, and a temperature exchange efficiency of 28 to 48% and enthalpy exchange efficiency of 57 to 85% for PHEX-B. The data shows that PHEX-A has higher efficiency than PHEX-B.