publications

2025

1. 

   Technoeconomic and Greenhouse Gas Impact Analysis of a Twin-Screw Compressor High Temperature Heat Pump for Spray Drying

   Joseph Tenpenny, Jan Spale, Davide Ziviani, and 1 more author

   2025

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   Process heat is one of the largest drivers of industrial energy demand and greenhouse gas emissions. Here, we consider a case study of a spray drying facility that requires 880 kW of heat from 8AM-5PM every day, and examine the potential costs and emissions impacts of adopting a high temperature heat pump (HTHP) to provide some of this process heat. For this type of facility, we generate the natural gas and electricity demand, accounting for both heating efficiency of a natural gas burner system or the coefficient of performance (COP) of the HTHP system, respectively. Using this information about the quantity and timing of natural gas and electricity demand, we then consider the private energy costs to operate spray drying systems with HTHP and natural gas heaters. In addition to the private costs of operating spray dryer systems, we consider the greenhouse gas emissions of the natural gas and the electricity used to meet the heat demand. Using both the private and social costs associated with natural gas and HTHP spray drying systems, we calculate the net present value of switching to HTHP. We find that the private costs of operating a HTHP are higher than the cost of operating a natural gas-fired spray dryer in all subregions, but, when we consider the social costs of greenhouse gas emissions, there are several subregions with net benefits from HTHP systems.

2024

1. 

   Exploratory study on low-GWP working fluid mixtures for industrial high temperature heat pump with 200 °C supply temperature

   Jan Spale, Andreas J. Hoess, Ian H. Bell, and 1 more author

   Energy, Nov 2024

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   The development of an industrial high temperature heat pump (HTHP) using a subcritical vapor-compression cycle (VCC) for process heat delivery at 200 °C faces significant challenges due to the scarcity of suitable single-component working fluids. These challenges are further compounded by safety, environmental concerns, material and lubrication oil compatibility and cost considerations. In response, this study investigates the potential of various fluid mixtures to meet these stringent criteria. Using the REFPROP and Cantera software libraries, a Python code was developed to simulate a simplified HTHP VCC with an advanced cycle architecture and assess the flammability risks of the proposed mixtures. Ten single-component fluids of two different families of compounds, hydrocarbons (HCs) and hydro(chloro)fluoroolefins (H(C)FOs), were pre-selected as promising candidates as mixture components. From these, over 460,000 binary, ternary, and quaternary mixtures were generated and evaluated for cycle performance. Although no mixture perfectly met all the predefined criteria, a binary blend of cyclopentane and R1336mzz(Z) in a mole fraction of 0.68 and 0.32, respectively, emerged as the most promising candidate. This mixture demonstrated the best balance of performance and safety under the imposed constraints and is selected for further experimental investigation and validation in a specially designed test rig.

2. 

   Concept and Design of a Velocity Compounded Radial Four-Fold Re-Entry Turbine for Organic Rankine Cycle (ORC) Applications

   Philipp Streit, Andreas P. Weiß, Dominik Stümpfl, and 4 more authors

   Energies, Jan 2024

   Number: 5 Publisher: Multidisciplinary Digital Publishing Institute

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   The energy sector faces a pressing need for significant transformation to curb CO2 emissions. For instance, Czechia and Germany have taken steps to phase out fossil thermal power plants by 2038, opting instead for a greater reliance on variable renewable energy sources like wind and solar power. Nonetheless, thermal power plants will still have roles, too. While the conventional multistage axial turbine design has been predominant in large-scale power plants for the past century, it is unsuitable for small-scale decentralized projects due to complexity and cost. To address this, the study investigates less common turbine types, which were discarded as they demonstrated lower efficiency. One design is the Elektra turbine, characterized by its velocity compounded radial re-entry configuration. The Elektra turbine combines the advantages of volumetric expanders (the low rotational speed requirement) with the advantages of a turbine (no rubbing seals, no lubrication in the working fluid, wear is almost completely avoided). Thus, the research goal of the authors is the implementation of a 10 kW-class ORC turbine driving a cost-effective off-the-shelf 3000 rpm generator. The paper introduces the concept of the Elektra turbine in comparison to other turbines and proposes this approach for an ORC working fluid. In the second part, the 1D design and 3D–CFD optimization of the 7 kW Elektra turbine working with Hexamethyldisiloxane (MM) is performed. Finally, CFD efficiency characteristics of various versions of the Elektra are presented and critically discussed regarding the originally defined design approach. The unsteady CFD calculation of the final Elektra version showed 46% total-to-static isentropic efficiency.

2023

1. 

   Experimental development of a lithium bromide absorption power cycle

   V. Novotny, J. Spale, J. Pavlicko, and 2 more authors

   Renewable Energy, Jan 2023

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2022

1. 

   Conversion of combined heat and power coal-fired plants to Carnot batteries - Prospective sites for early grid-scale applications

   A. Basta, V. Basta, J. Spale, and 2 more authors

   Journal of Energy Storage, Jan 2022

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2. 

   Scaling up a woodchip-fired containerized CHP ORC unit toward commercialization

   J. Spale, V. Vodicka, Z. Zeleny, and 3 more authors

   Renewable Energy, Jan 2022

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3. 

   Experimental investigation of combustion engine with novel jacket and flue gas heat recovery

   J. Spale, J. Pavlicko, V. Vodicka, and 2 more authors

   Energy Reports, Jan 2022

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4. 

   Review of Carnot Battery Technology Commercial Development

   V. Novotny, V. Basta, P. Smola, and 1 more author

   Energies, Jan 2022

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2021

1. 

   Direct integration of an organic Rankine cycle into an internal combustion engine cooling system for comprehensive and simplified waste heat recovery

   V. Novotny, J. Spale, D.J. Szucs, and 2 more authors

   Energy Reports, Jan 2021

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2. 

   Absorption power and cooling combined cycle with an aqueous salt solution as a working fluid and a technically feasible configuration

   V. Novotny, D.J. Szucs, J. Špale, and 2 more authors

   Energies, Jan 2021

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3. 

   Absorption power cycle with a 3D-printed plastic micro turboexpander - Considerations, design and first experimental results

   V. Novotny, J. Spale, D. Suchna, and 3 more authors

   Jan 2021

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4. 

   3D printed radial impulse cantilever micro-turboexpander for preliminary air testing

   J. Spale, V. Novotny, V. Mares, and 1 more author

   Jan 2021

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5. 

   Experience from set-up and pilot operation of an in-house developed biomass-fired ORC microcogeneration unit

   J. Mascuch, V. Novotny, J. Spale, and 2 more authors

   Renewable Energy, Jan 2021

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6. SCALING-UP A BIOMASS FIRED MICRO-CHP ORC FOR BETTER PERFORMANCE TOWARDS COMMERCIALIZATION

   J. Mascuch, J. Spale, V. Vodicka, and 2 more authors

   Jan 2021

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7. EXPERIMENTAL INVESTIGATION OF A KW SCALE ABSORPTION POWER CYCLE WITH LIBR SOLUTION

   V. Novotny, J. Spale, J. Pavlicko, and 2 more authors

   Jan 2021

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2020

1. 

   Customized ORC micro turbo-expanders - From 1D design to modular construction kit and prospects of additive manufacturing

   A.P. Weiß, V. Novotný, T. Popp, and 4 more authors

   Energy, Jan 2020

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2. 

   Experimental development of a kilowatt-scale biomass fired micro – CHP unit based on ORC with rotary vane expander

   J. Mascuch, V. Novotny, V. Vodicka, and 2 more authors

   Renewable Energy, Jan 2020

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3. 

   Intermediate pressure reboiling in geothermal flash plant for increased power production and more effective non-condensable gas abatement

   V. Novotny, M. Vitvarova, J. Spale, and 1 more author

   Energy Reports, Jan 2020

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4. 

   Uncommon turbine architectures for distributed power generation - Development of a small velocity compounded radial re-entry turbine

   A.P. Weiss, P. Streit, T. Popp, and 4 more authors

   Archives of Thermodynamics, Jan 2020

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5. Investigation of novel configuration for dual organic rankine cycle configurations for maximization of waste heat utilization

   V. Novotny, D.J. Szucs, J. Spale, and 3 more authors

   Jan 2020

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2019

1. 

   Design and manufacturing of a metal 3D printed KW scale axial turboexpander

   V. Novotny, M. Vitvarova, M. Kolovratnik, and 6 more authors

   Jan 2019

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2. 

   3D printing in turbomachinery: Overview of technologies, applications and possibilities for industry 4.0

   V. Novotny, J. Spale, B.B. Stunova, and 3 more authors

   Jan 2019

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