Imants Kaldre

Dr. Imants Kaldre

Institute of Physics, University of Latvia, Jelgavas Street 3, LV-1004 Riga, Latvia
orcid

Research Focus & Metrics

Academic Career Length

15Years (2012-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

View All Publications
26 November 2019 in Scientific Reports
Verified
Journal Article
Open access
PDF file
EPErnests Platacis
Ernests Platacis
Imants KaldreImants Kaldre
Imants Kaldre
EBErvīns Blumbergs
Ervīns Blumbergs
LGLinards Goldšteins
Linards Goldšteins
VSVera Serga
Vera Serga
Titanium is widely used in specific applications due to its high strength, low density and good chemical stability. Despite it is one of the most abundant elements in the earth’s crust, it is very expensive, because production of pure metallic titanium is very complex. Kroll process is the way how most of the titanium is produced nowadays. Shortages of this process are that it is batch process and it is very energy exhaustive, because titanium sponge material after reduction reaction needs complex post processing to isolate pure titanium. In this work we describe and experimentally investigate technology for Ti production from titanium tetrachloride using combined Kroll and electroslag process. Such process allows to achieve better reaction product separation by molten slag and process can potentially be continuous, thus technological process to produce metallic titanium can be significantly shortened.

18 December 2024 in Technologies
Verified
Journal Article
Open access
PDF file
VBValerijs Bezrukovs
Valerijs Bezrukovs
VBVladislavs Bezrukovs
Vladislavs Bezrukovs
Marina KonuhovaMarina Konuhova
Marina Konuhova
DBDeniss Bezrukovs
Deniss Bezrukovs
Imants KaldreImants Kaldre
Imants Kaldre
Anatoli I PopovAnatoli I Popov
Anatoli I Popov
This paper presents the results of numerical simulations examining the thermodynamic processes during hydraulic hydrogen compression, using COMSOL Multiphysics® 6.0. These simulations focus on the application of hydrogen compression systems, particularly in hydrogen refueling stations. The computational models employ the CFD and heat transfer modules, along with deforming mesh technology, to simulate gas compression and heat transfer dynamics. The superposition method was applied to simplify the analysis of hydrogen and liquid piston interactions within a stainless-steel chamber, accounting for heat exchange between the hydrogen, the oil (working fluid), and the cylinder walls. The study investigates the effects of varying compression stroke durations and initial hydrogen pressures, providing detailed insights into temperature distributions and energy consumption under different conditions. The results reveal that the upper region of the chamber experiences significant heating, highlighting the need for efficient cooling systems. Additionally, the simulations show that longer compression strokes reduce the power requirement for the liquid pump, offering potential for optimizing system design and reducing equipment costs. This study offers crucial data for enhancing the efficiency of hydraulic hydrogen compression systems, paving the way for improved energy consumption and thermal management in high-pressure applications.

30 October 2024 in Preprints.org
Verified
Preprint
Open access
PDF file
VBValerijs Bezrukovs
Valerijs Bezrukovs
VBVladislavs Bezrukovs
Vladislavs Bezrukovs
Marina KonuhovaMarina Konuhova
Marina Konuhova
DBDeniss Bezrukovs
Deniss Bezrukovs
Imants KaldreImants Kaldre
Imants Kaldre
Anatoli I PopovAnatoli I Popov
Anatoli I Popov
This paper presents the results of numerical simulations examining the thermodynamic processes during hydraulic hydrogen compression, using COMSOL Multiphysics® 6.0. These simulations focus on the application of hydrogen compression systems, particularly in hydrogen refueling stations. The computational models employ the CFD and Heat Transfer modules, along with deforming mesh technology, to simulate gas compression and heat transfer dynamics. The superposition method was applied to simplify the analysis of hydrogen and liquid piston interactions within a stainless-steel chamber, accounting for heat exchange between the hydrogen, the working fluid, and the cylinder walls. The study investigates the effects of varying compression stroke durations and initial hydrogen pressures, providing detailed insights into temperature distributions and energy consumption under different conditions. The results reveal that the upper region of the chamber experiences significant heating, highlighting the need for efficient cooling systems. Additionally, the simulations show that longer compression strokes reduce the power requirement for the liquid pump, offering potential for optimizing system design and reducing equipment costs. This study offers crucial data for enhancing the efficiency of hydraulic hydrogen compression systems, paving the way for improved energy consumption and thermal management in high-pressure applications.

1 July 2017 in IOP Conference Series: Materials Science and Engineering
Verified
Conference Paper
Open access
PDF file
ABA Bojarevičs
A Bojarevičs
RBR Baranovskis
R Baranovskis
Imants KaldreImants Kaldre
Imants Kaldre
MMM Milgrāvis
M Milgrāvis
TBT Beinerts
T Beinerts
To achieve a uniform liquid metal composition and temperature distribution, stirring is often necessary for industrial processes. Here, a novel permanent magnet system for liquid melt stirring is proposed. It promises very low energy consumption and options for multiple different flow types compared to traditional travelling magnetic field inductors or mechanical stirrers. The proposed system has a simple design: it consists of two rotating permanent magnet cylinders, which are magnetized transversely to the axis of the cylinders. The experimental device was developed and tested under various regimes using GaInSn alloy in a cylindrical crucible. Aluminum stirring by permanent magnets in laboratory scale is tested, and stirring impact on directional solidification of metallic alloys is experimentally investigated.

2 February 2023 in Crystals
Verified
Journal Article
Open access
PDF file
Mikus MilgravisMikus Milgravis
Mikus Milgravis
Ivars KrastinsIvars Krastins
Ivars Krastins
Imants KaldreImants Kaldre
Imants Kaldre
MKMatiss Kalvans
Matiss Kalvans
ABAndris Bojarevičs
Andris Bojarevičs
TBToms Beinerts
Toms Beinerts
Electromagnetic methods can be used to affect the solidification of metallic alloys. Combined alternating and static (DC) magnetic fields can induce pressure waves in liquid metals in a contactless manner, refining grain structure, preventing component segregation, and dispersing added particles. Here, the possibility of using a pulsed magnetic field in combination with a DC magnetic field to improve the solidification structure of metals is investigated. This enables achieving higher pressure amplitude and liquid movement within the whole crucible volume at the same power consumption. This can be a prospective way to achieve a fine-grained and a more homogeneous microstructure of metallic alloys as well as disperse added particles. In this work, analytical description of the phenomena and numerical modeling of the pressure amplitude and melt motion has been performed. A series of experiments have been carried out to demonstrate the effect of such interaction on the solidified metal microstructure. It is found that a combination of pulsed and DC magnetic fields creates strong compression and expansion of the liquid metal. Metals solidified under such interaction exhibit finer grain structure in Sn-Pb alloy and improved TiB2 particle distribution in 6061 aluminum alloy.
1

7 April 2020 in JOM
Verified
Journal Article
Closed access
PDF file
Imants KaldreImants Kaldre
Imants Kaldre
ABAndris Bojarevics
Andris Bojarevics