Publications

10. Conference Paper: Veronika Wilk, Franz Helminger, Bernd Windholz, Andreas Sporr, Michael Lauermann, Thomas Fleckl, Wärmerückgewinnung für Trocknungsprozesse mit Hochtemperatur-Wärmepumpen (Heat recovery for drying processes with high-temperature heat pumps), Proceedings of the 27th Conference of the Research Program Heat Pumps and Refrigeration of the Swiss Federal Office of Energy (BFE), 23.06.2021, Digital event.

Abstract:

At 12-25 %, drying processes account for a significant share of the national industrial energy demand in developed countries. With high-temperature heat pumps, these processes can be operated much more efficiently through heat recovery. This requires high heat utilization temperatures. In the DryFiciency project, high-temperature heat pumps capable of delivering up to 160 °C have been developed and demonstrated in a brick dryer, as well as a starch dryer. Initial operating results have shown that the heat pump provides heat utilization temperatures of 120 – 160 °C in steady-state operation without fluctuations in the heat source or heat sink. COPs of 2.7 – 4.7 are achieved. If the operating results of the DryFiciency systems are transferred to drying processes in general, energy cost reductions of up to 58 % can already be achieved based on average current Austrian energy prices. Also with regard to future increasing CO2 costs, the heat pump is a future-proof heat supply system for drying plants. With higher CO2 prices, energy cost reductions of up to 75% are possible.

This paper is available in German only. The proceedings will be published here soon.

9. Conference Paper: Veronika Wilk, Franz Helminger, Michael Lauermann, Andreas Sporr, Bernd Windholz, High temperature heat pumps for drying – first results of operation in industrial environment, Proceedings from the 13th IEA Heat Pump Conference, 26.-29.4.2021, Hybrid event.

Abstract: 

Heat pumps can make an important contribution to increasing the efficiency of industrial processes and avoiding CO2 emissions and therefore are considered as an important element for industrial heat supply by valorizing waste heat. Heat utilisation temperatures above 120°C will significantly expand the field of application for heat pumps in industry.
This article presents the first results of operation of the H2020 project DryFiciency. Two closed loop high temperature heat pumps with a heating capacity of 400 kW and heat supply temperatures up to 160°C are being developed, built and operated. The heat pumps are integrated in industrial drying processes in two Austrian companies, at AGRANA Stärke GmbH in Pischelsdorf and Wienerberger AG in Uttendorf, recovering waste heat available on site. Commissioning of the heat pumps will start in November 2019. In this article, a first assessment of the operation of one of the heat pumps is presented.

The conference proceedings are available for purchase here.

8. Conference paper: Veronika Wilk, Franz Helminger, Michael Lauermann, High temperature heat pumps for industrial processes – application and potential, Proceedings of ECEEE Industrial Summer Study, 14-19.09.2020, Digital event. 

Abstract:

Industrial heat pumps convert unused waste heat into valuable process heat and therefore, they increase process efficiency and the share of electrified processes. With a total of 25 % of the energy demand in the European Union, industry is a key player to achieve the climate goals of the European Union. The share of heat pumps in Austrian industry is steadily increasing. Typically, heat pumps are applied in the food industry with heat supply temperatures of up to 80 °C or for district heating applications. High temperature heat pumps that deliver process heat up to 160 °C offer a larger range of applications in industrial processes and are currently being developed.

DryFiciency is an H2020 demonstration project, where two high temperature heat pump demonstrators are developed and operated in drying processes in a real industrial environment. This work presents the techno-economic assessment of the first operation period of the DryFiciency heat pump. It is integrated at a production site of Wienerberger in Austria und supplies hot air for brick drying. The DryFiciency heat pump allows for significant reductions of end energy consumption (from 66 % at a heat supply temperature of 160 °C to 81 % at 120 °C) and CO2 emissions (67–82 %) compared to a natural gas burner. Due to the recovery of waste heat and the prospect of increasing shares of renewable electricity production and increasing CO2 costs, the heat pump is a future-proof process heat supply system. Based on average Austrian energy prices, cost reductions in the range of 12–50 % can be achieved. With higher CO2 prices, up to 28– 59 % of energy cost reductions are possible.

The paper is available for download. Click here.

7. Conference paper: Martin Koller, Annemarie Schneeberger, Veronika Wilk, 2020, Marktpotenzial für Hochtemperatur-Wärmepumpen in Europa (Market potential for high temperature heat pumps in Europe), 16th Symposium EnInnov, 12-14.02.2020, Graz

Abstract:

Motivation: With 27% of the final energy consumption, industry is the second largest energy consumer in Austria after the transport sector. This sector should be supplied with renewable energy in the long term to achieve the international climate protection goals. Heat pumps for industrial applications are seen as a key element in the future energy infrastructure and can make an important contribution to increasing the efficiency of industrial processes and avoiding CO2 emissions. A recently published study on how Austrian industry can be fully supplied with renewable energy underlines the importance of high-temperature heat pumps as a basic technology for recovering waste heat and increasing energy efficiency. In the H2020 project DryFiciency, high-temperature heat pumps delivering flow temperatures of up to 160°C are developed and demonstrated first-time in an industrial environment. After successful demonstration, this technology will be brought to market. For stakeholders, such as component manufacturers and equipment manufacturers, an evaluation of the sales potential of this technology is therefore of great importance.

Methodology: In order to estimate the market potential, a comprehensive literature review was conducted. The data thus obtained was checked for plausibility and further processed by, for example, taking country-specific energy prices into account and performing a sensitivity analysis. This results in the heat demand that can be covered by high-temperature heat pumps. This demand is used to estimate the potential sales of heat pump systems in Europe.

Results: There is already some research work that investigated the process heat demand in energy intensive industry. Here the heat demand is differentiated by different industrial sectors, countries and also temperature ranges. The high temperature heat pumps, for which the market potential is to be determined, reach sink temperatures of up to 160°C. Heat source temperatures of 80°C are assumed. Therefore, for a complete consideration, the waste heat potential in the corresponding temperature range is also required. However, data on waste heat potential are available in much less detail. Based on a paper in which the potential for high-temperature heat pumps in Europe was investigated by balancing heat demand and waste heat generated, further considerations were made to infer the heat supply and estimates for the potential sales of heat pump systems in Europe. In the future scenario considered, high-temperature heat pumps in industry are competitive with a fossil reference technology for heat supply (gas boilers) in almost all EU countries with the assumptions made (rising energy and CO2 prices). Thus, about 10 % of the heat demand in the range of 100 – 200°C of the European industry could be supplied by high temperature heat pumps in future.

This paper is available in German only. Click here.

6. Conference paper: Veronika Wilk, Michael Lauermann, Franz Helminger, 2019, Decarbonization of industrial processes with heat pumps, Proceedings of the 25th IIR International Congress of Refrigeration: Montreal, Canada, August 24th-30th, 2019.

Abstract:

To counteract climate change the efficient use of energy in industry becomes increasingly important. Heat pumps enable decarbonized industrial processes by replacing fossil fuels with electricity. DryFiciency develops and demonstrates high temperature heat pumps using OpteonMZ as refrigerant to supply hot water up to 160°C. Heat pumps will be installed in drying processes for starch and bricks in two Austrian companies in spring 2019. We present design considerations for high temperature heat pumps, as well as the expected CO2 reductions and primary energy savings. Calculations are based on numerical process simulation. At the two demo-sites CO2 emission reductions up to 40-90% and primary energy reduction from 20-80% can be achieved compared to natural gas. Similar considerations are presented for larger roll-out in EU. Heat pumps improve the energy efficiency of industrial processes significantly. The demonstrators are an important step in the development of viable industrial solutions.

This paper is available for download. Click here.

5. Conference paper: Michael Bantle, Christian Schlemminger, Cecilia Gabielii, Marcel Ahrens, Kjetil Evenmo, 2019, Turbo-compressor for R-718: Simulation and verification of a two-stage steam compression cycle, Proceedings of the 25th IIR International Congress of Refrigeration: Montreal, Canada, August 24th-30th, 2019.

Abstract:

Water (R-718) is a safe and energy-efficient refrigerant. Mechanical vapour recompression (MVR), an open-loop heat pump using R718, can significantly reduce the energy consumption for steam-heated processes like drying, pasteurization, evaporation or distillation. However, the existing compression technology is not cost-efficient, especially in the capacity range from 500 kW to 4 MW. Therefore, a novel two-stage turbo-compressor system, developed for application in industrial superheated steam drying and based on mass-produced automotive turbocharger technology, was developed. Its performance was evaluated in a test facility, showing that it is possible to compress superheated steam from atmospheric pressure up to 3 bar, delivering 300 kW at 133°C, with a COP of 5.9, an isentropic efficiency of 74% and a Carnot efficiency of 48%. With an estimated investment cost of 150 €/kW installed heating capacity, the system clearly has the potential of being a cost-effective solution for heat recovery in steam-heated industrial processes.

To be purchased under: http://www.iifiir.org/

4. Conference paper: Michael Bantle, Christian Schlemminger, Ignat Tolstorebrov, Marcel Ahrens, Kjetil Evenmo, 2018, Performance evaluation of two stage mechanical vapour recompression with turbo-compressors, Proceedings of the 13th IIR Gustav Lorentzen Conference, Valencia, 2018.

Abstract:

Mechanical Vapour Recompression (MVR) is an open loop heat pump system using water (R718) as working fluid, one of the most abundant and safest refrigerant on the planet. The concept can significantly reduce the energy consumption for steam based processes like drying, pasteurization, evaporation or distillation but also for steam production itself. However, the compression technology is commonly not cost efficient especially for small scale productions in the capacity range from 500 kW to 4 MW.  A two stage turbo-compression system was developed and tested based on mass produced automotive turbocharger technology. The turbo-compressor of the first stage reached a pressure ratio of 1.68 and is designed for a mass flow of 400-600 kg/h superheated steam. The second stage turbo-compressor had an identical design and achieved a pressure ration of 1.72. Between compression stage one and two de-superheating is applied by water injection. With the developed system it is possible to compress superheated steam from atmospheric pressure to above 2.9 bar, where it can be condensed at a temperature of 132°C. The COP of the performed investigation was 7.8, when the achievable condensation energy is compared to the total amount of energy supplied to the system. Without the losses in the inverters, motor and gearbox the COP is 9.4, which is the COP when only the isentropic losses of compression are considered. This means that the isentropic efficiency is around 70% of the Carnot efficiency and the system efficiency is still 58% of the Carnot efficiency, even when all loss are considered.

The conference proceedings are available for purchase http://www.proceedings.com/40853.html

3. Master thesis: Ahrens Ulrich Marcel, 2018, Experimental and numerical analysis of a two-stage turbo compressor system for industrial superheated steam drying, Technical University of Braunschweig.

The aim of this master’s thesis was the experimental analysis of the turbo compresso rtechnology performance as well as the development of a numerical turbo compressor model and the evaluation of the two-stage turbo compressor performance. To analyse the performance of the turbo compressors technology, experiments were performed at the test facility developed by SINTEF Energy Research. A suitable numerical turbo compressor model was identified and validated for the development of a system model. The achieved results and experiences were used for the evaluation of the two-stage turbo compressor performance.

The experiments demonstrated a stable operation of the two-stage turbo compressor system. The compressor maps have been created which allow an analysis of the performance and operating range of the turbo compressor. The numerical models were able to reproduce the results in a good approximation and allowed the estimation of further operating points. During this elaboration, the system was able to compress superheated steam from atmospheric pressure to above 3.0 bar, where it can be condensed at a saturation temperature of 133.5 °C. The COP of the performed investigation was 5.9, when the achievable condensation energy is compared to the total amount of energy supplied to the system.

Find the publication on Zenodo – click here

2. Conference paper: Veronika Wilk, Michael Lauermann, Franz Helminger, 2018, Design zweier Wärmepumpen-Demoanlagen für die industrielle Trocknung (Design of two heat pump demonstration systems for industrial drying), Proceedings of DKV Tagung 2018, 21-23.11.2018, Aachen, Germany.

The paper focuses on the design of two high temperature heat pump systems to be demonstrated first-time in industrial drying applications. The drying processes of the demo sites at Agrana Stärke GmbH and Wienerberger AG are explained with and without heat pump integration, the design questions to be considered are elaborated on, and the two compressors to be demonstrated first-time – a semi-hermetic scroll compressor from Bitzer and a piston compressor from Viking Heat Engines A/S – are presented. In addition, possible refrigerant circuit configurations including their pros and cons are elaborated. Finally, an outlook on the next steps to be taken within the project is provided.

This paper is available in German only. The conference proceedings are available for purchase http://www.proceedings.com/1430.html

1. Conference paper: Michael Bantle, Christian Schlemminger, Marcel Ahrens, Kjetil Evenmo, 2018, Kennfeld und Leistungsanalyse einer zweistufigen Turbokompressor- Brüdenverdichtung (Characteristic map and performance analysis of a two-stage turbo compressor vapour recompression), Proceedings of DKV Tagung 2018, 21-23.11.2018, Aachen, Germany.

The paper focuses on the potential of a two-stage turbo compressor vapour recompression for industrial applications and elaborates on the performance data achieved with a novel turbo-compressor developed by Rotrex A/S within the DryFiciency project. The set-up of the lab environment of the mechanical vapour recompression (MVR) system is presented. The characteristic map and performance data of the turbo compressors tested in 2-stages is explained in detail.

This paper is available in German only. The conference proceedings are available for purchase http://www.proceedings.com/1430.html