{"id":258,"date":"2026-07-23T11:41:08","date_gmt":"2026-07-23T11:41:08","guid":{"rendered":"https:\/\/hp2mix.dk\/?page_id=258"},"modified":"2026-08-26T10:56:40","modified_gmt":"2026-08-26T10:56:40","slug":"hp2mix-partners-kelvion-and-dti-collaborate-on-protoype-testing","status":"publish","type":"page","link":"https:\/\/hp2mix.dk\/?page_id=258","title":{"rendered":"HP2MIX Partners Kelvion and DTI Collaborate on Protoype Testing\u202f"},"content":{"rendered":"\n
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In May\u202f2026, representatives from Kelvion and Danish Technological Institute (DTI) met at DTI\u2019s facilities in Aarhus. The\u202fpurpose of the\u202fvisit was\u202fto inspect\u202fthe prototype setup\u202fdeveloped\u202fwithin the\u202fHP2MIX\u202fproject\u202fand\u202fto\u202fcarry out\u202finitial\u202ftechnical evaluations\u202fof the system\u2019s heat exchangers under zeotropic operating conditions.\u202f <\/p>\n\n\n\n

The\u202fvisit\u202fprovided an opportunity for the\u202fproject partners\u202fto\u202falign\u202fon\u202ftechnical details and meet in person. Kelvion was represented by Key Account Manager Lars Knudsen and Thermal Engineer Prof. Dr\u202fSepehr\u202fForoushani. The DTI project team was represented by Project Manager Pierre-Jean\u202fDel\u00eatre\u202fand Senior Project Manager J\u00f3hannes Krist\u00f3fersson.\u202f <\/p>\n\n\n\n

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The Critical Role of Heat Exchangers in Systems\u202fUsing Zeotropic Mixtures\u202f <\/strong><\/h2>\n\n\n\n

In conventional heat pumps, pure refrigerants evaporate and condense at a constant temperature. The HP2MIX project, however,\u202futilizes\u202fnatural zeotropic mixtures (based on\u202fhydrocarbons). These mixtures experience a temperature glide during phase change, meaning that the temperature changes as the fluid evaporates or condenses.\u202f <\/p>\n\n\n\n

By matching this temperature glide with the temperature changes of the heat source and heat sink, exergy losses in the heat exchangers can be significantly reduced. This glide-matching is the primary mechanism for achieving the project’s target of a 20% to 30% increase in Coefficient of Performance (COP).\u202f <\/p>\n\n\n\n

However,\u202futilizing\u202fzeotropic mixtures introduces specific technical challenges for heat exchanger design, which are a major focus of the partnership:\u202f <\/p>\n\n\n\n

– Mass Diffusion Resistance:<\/strong>\u202f
During phase change, zeotropic mixtures experience mass diffusion resistance, which typically degrades the heat transfer coefficient compared to pure fluids. To prevent the need for excessively large and costly equipment, the plate heat exchangers must be geometrically\u202foptimized\u202fto\u202fmaintain\u202fhigh heat transfer rates.\u202f <\/p>\n\n\n\n

– Refrigerant Charge Minimization:\u202f<\/strong>
Because the project\u202futilizes\u202fflammable hydrocarbons, safety is a key parameter. The project targets a 20% reduction in refrigerant charge per kW of heating capacity. This requires the development of compact plate heat exchangers with minimal internal volume that still\u202fdeliver\u202foptimal\u202fthermal performance.\u202f <\/p>\n\n\n\n

– Phase Distribution:\u202f<\/strong>
Ensuring a uniform distribution of the liquid and\u202fvapour\u202fphases across the heat exchanger plates is critical to\u202fmaintaining\u202fstable operation and avoiding local\u202fdry-outs.\u202f <\/p>\n\n\n\n

– Refrigerant\u202fGlide:<\/strong>
Provides\u202fbenefits for the system but also\u202frepresents\u202fa risk of freezing of the heat exchanger in case of\u202fe.g.\u202fa large subcooling degree.\u202f <\/p>\n\n\n\n

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Inspection and Freezing Tests on the\u202f20 kW\u202fPrototype<\/strong>\u202f <\/h2>\n\n\n\n

The main focus of the visit was the 20 kW HP2MIX prototype heat pump,\u202fcurrently\u202finstalled in DTI\u2019s laboratory.\u202fThis small-scale setup serves as a testbed to\u202fvalidate\u202fcomponent\u202fdesigns, including Kelvion’s customized brazed plate heat exchangers, before scaling up\u202fto larger systems.\u202f <\/p>\n\n\n\n

During the visit, the partners inspected the physical installation, the measuring equipment, and the project\u2019s online data platform.\u202f <\/p>\n\n\n\n

The team also conducted a short freezing test on the evaporator. By systematically lowering the evaporating temperature to induce ice formation, the partners collected data to:\u202f <\/p>\n\n\n\n

– Identify\u202fthe physical and thermal operating limits of the heat exchanger.\u202f <\/p>\n\n\n\n

– Gather data to help prevent freezing in future operations.\u202f <\/p>\n\n\n\n

– Support the development of operating recommendations and control strategies for\u202fend-users.\u202f <\/p>\n\n\n\n

Regarding the testing platform, Prof. Dr Sepehr Foroushani noted: <\/p>\n\n\n\n

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I really like\u00a0the\u00a0test setup and data visualization tool\u00a0at DTI. It\u2019s a bit daunting the first time with so many options, but already from the second time it was very intuitive and really useful.<\/p>\n<\/blockquote>\n\n\n\n

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From 20 kW Prototype to 500 kW Demonstration<\/strong>\u202f <\/h2>\n\n\n\n

The HP2MIX project\u202faims to support the decarbonisation of industrial process heat and district heating.\u202fThe data and insights gained from the 20 kW prototype tests in Aarhus will directly\u202fbe used to support the design of a\u202f500 kW\u202fdemonstration plant.\u202fThis full-scale system\u202fis planned for installation at one of\u202fInnargi’s\u202fgeothermal district heating sites\u202fto prove the technology’s performance and reliability under real-world conditions.\u202f <\/p>\n\n\n\n

For the HP2MIX project, the immediate next steps include:\u202f <\/p>\n\n\n\n

– Temperature Profile Testing:<\/strong>\u202f
Evaluating the remaining temperature profiles defined in the project (the\u202fInnargi\u202fgeothermal profiles).\u202f <\/p>\n\n\n\n

– Further Freezing Tests:\u202f<\/strong>
Carrying out freezing tests with different heat exchanger designs.\u202f <\/p>\n\n\n\n

– Liquid Distributor Evaluation:<\/strong>
Investigating how different liquid distributor configurations impact fluid distribution and heat transfer performance in the evaporator.\u202f <\/p>\n\n\n\n

During the laboratory visit, the partners also\u202ftook the opportunity to\u202finspect the\u202fFORCO2 rig.\u202fThis sister\u202fproject -\u202fwhich also counts both DTI and Kelvion as partners\u202f-\u202ffocuses on developing reversible CO2 chiller and heat pump units.\u202fKelvion\u202fand DTI\u202fplan to test additional heat exchangers on the FORCO2 rig in the near future, leveraging strong technical synergies between the two projects.\u202f <\/p>\n<\/div>\n<\/div>\n\n\n\n

Watch the video from the visit<\/h2>\n\n\n\n