Heat exchanger modelling
Creators: name: Söylemez, Engin
name: Carbonell, Daniel
name: Anton, Xabier Pena
Publisher: name: Zenodo
Year: 2023
Subjects: Modelling
CO2, R-744
Natural refrigerant
Tri-partite gas cooler
Heat recovery
Heat exchangers
Supercooler
dual source/sink

description: TRI-HP EU project aims to develop trigeneration integrated solutions that combine heating, cooling and electricity<br> generation based on heat pumps running with natural refrigerants and using multiple renewable energy<br> sources. Most of the developments of the project are focussed on the whole refrigerant cycle of the heat pumps<br> as well as on the heat exchangers used. Three innovative heat exchangers have been designed, manufactured,<br> and tested as stand-alone devices and implemented in heat pumps with nominal capacities of 10 kW within<br> the current project. The experimental results of the supercoolers have been published in [1] where all experimental data used here is accessible as open data.<br> One of the heat exchangers developed is based on brazed heat exchangers where icephobic coatings have been<br> applied to achieve high levels of supercooling in very compact heat exchangers typically used in residential heat<br> pumps. Several coatings were applied into plate heat exchangers, the so-called supercoolers, and were compared<br> to each other. The best coatings were applied in the evaporators of the heat pumps that were able to supercool<br> water in real dynamic conditions. In the present deliverable, a numerical model to predict the behaviour of supercoolers<br> is presented and validated with experimental data. Results show that the model presented here is able<br> to capture the main characteristics of the supercoolers assessed. The experimental results of the dual source/sink heat exchanger have been published in [2].<br> A second innovative heat exchanger is a dual source/sink unit able to use brine/water as well as air as heat sources<br> and sinks for heating and cooling, respectively. The idea is to be able to use ground sources as well as ambient air<br> as heat sources and sinks. This heat exchanger is key in the development of a dual source/sink heat pump which<br> has been manufactured and tested. This hybrid heat pump is fully reversible, and as such, the dual heat exchanger<br> needs to operate as an evaporator as well as a condenser. The design and sizing of this heat exchanger were based<br> on a numerical model developed in Modelica. The numerical model, as well as its validation in heating and cooling<br> models using both sources, is provided. <br> The third innovative heat exchanger is specially dedicated to transcritical CO<sub>2</sub> heat pumps. A tri-partite gas cooler<br> has been developed to provide space heating (SH) and domestic hot water (DHW) simultaneously in a<br> compact unit. The tri-partite gas cooler consists of three brazed heat exchangers connected in a particular form.<br> The first gas cooler is used to preheat DHW, the second one is used to provide SH, and the third one is to reheat<br> DHW. The three gas coolers are connected in series on the CO<sub>2</sub> site such that the hottest part of the CO<sub>2</sub> side is<br> connected to the third gas cooler. The CO<sub>2</sub> is then cooled from the gas cooler third to the one. experimental<br> results of the tri-partite gas coolers have been published in [3].