A new journal publication presenting HYBUILD outcomes has just been released !
Integration of a three-media refrigerant/phase change material (PCM)/water heat exchanger (RPW-HEX) in the hot superheated section of a heat pump (HP) system is a promising approach to save energy for domestic hot water (DHW) generation in multi-family houses. The RPW-HEX works as a desuperheater and as a latent thermal energy storage in the system. The latent thermal energy storage is charged during heating and cooling operation and discharged for DHW production. For this purpose, the water side of the RPW-HEX is connected to decentralized DHW storage devices. DHW consumption, building standards and climate, energy prices, material costs, and production costs are the constraints for the selection of the optimal storage size and RPW-HEX design. This contribution presents the techno-economic analysis of the RPW-HEX integrated into an R32 air source HP. With the aid of experimentally validated dynamic computer models, the optimal sizing of the RPW-HEX storage is discussed to maximize energy savings and to minimize the investment costs. The results are discussed in the context of a return of investment analysis, practical implementation aspects and energetic potential of the novel technology.
A new journal publication presenting HYBUILD outcomes has just been released: Solar cooling systems are a promising solution for reducing the electrical consumption of conventional building cooling systems. Among various alternatives, photovoltaic driven vapour compression chillers are currently the most mature and economically feasible solar cooling technology. This study focuses on the semi-dynamic modelling of a vapour compression chiller coupled with a novel refrigerant-phase change material (PCM)-water heat exchanger (RPW-HEX) which replaces the conventional chiller’s evaporator, allowing the efficient storage of the produced cooling energy. A custom-build lumped parameter model was developed in TRNSYS and was used to assess the performance of the proposed system on annual basis. Using as benchmark a conventional PV driven vapour compression chiller with electrical storage, the retrofitted hybrid storage system showed improved performance, limiting the cooling demand peaks and enhancing the solar fraction, especially for partial cooling loads. Last, a comparison of the PCM thermal energy storage to conventional batteries was carried out, leading to enhanced performance characteristics for the latter.
A new journal paper presenting HYBUILD results has been released in the Energies journal.
The area-proportional baseline method generates phase fraction–temperature curves from heat capacity data of phase change materials. The curves describe the continuous conversion from solid to liquid over an extended temperature range. They are consistent with the apparent heat capacity and enthalpy modeling approach for the numerical solution of heat transfer problems. However, the curves are non-smooth, discrete signals. They are affected by noise in the heat capacity data and should not be used as input to continuous simulation models. This contribution proposes an alternative method based on spline approximation for the generation of consistent and smooth phase fraction–temperature, apparent heat capacity–temperature and enthalpy–temperature curves. Applications are presented for two commercial paraffins from Rubitherm GmbH considering heat capacity data from Differential Scanning Calorimetry and 3-layer-calorimetry. Apparent heat capacity models are validated for melting experiments using a compact heat exchanger. The best fitting models and the most efficient numerical solutions are obtained for heat capacity data from 3-layer-calorimetry using the proposed spline approximation method. Because of these promising results, the method is applied to melting data of all 44 Rubitherm paraffins. The computer code of the corresponding phase transition models is provided in the Supplementary Information.
The conservation and rehabilitation of buildings of vernacular architecture is a sustainable approach, not only because it leaves a small ecological footprint, compared to the erection of new buildings, but also due to the passive bioclimatic design features integrated in vernacular buildings. This paper will investigate the thermal performance of vernacular architecture in lowland area in diverse climatic contexts.
The findings of the current research are based on an on-site investigation carried out in a representative vernacular building that is going to be upgraded to a hands-on technology exhibition area of renewable energy systems complimented with visual means to enhance the experience of visitors under a Research European Programme (Horizon 2020). The current study provides a basis for the formulation of a site-specific design strategy to improve thermal conditions and achieve energy conservation within lowland constructions in diverse climatic conditions. Understanding and analysing the thermal behaviour of these spaces is the first step towards this strategy. The quantitative analysis reveals the various challenges faced and opportunities provided by lowland structures and contributes to informing current design policies. Moreover, the analysis will inform the sizing of the technical systems throughout the year.
Work is ongoing at the Langenwang Austrian pilot, to prepare the installation of the HYBUILD hybrid storage system.
The continental climate system will be installed at this pilot site. The maximum heating power consumption expected after the foreseen retrofitting operations is 10 kW. The following technologies will be applied in the building: PV, PCM thermal latent storage, Heat pump.
One of the main limitations for the wide diffusion of sorption systems, either as stand-alone and in hybrid configurations, is the low heat transfer inside the adsorber, as well as the low volumetric cooling power.
In this context, HYBUILD partners (CNR ITAE, AKG, Fahrenheit and Mikrometal) have just released a new scientific paper which reports the experimental activity on four different advanced configurations for the adsorber, based on microchannel heat exchangers where the gap between the channels is filled with porous structures where zeotypes of SAPO-34 family were synthetized.
The porous structures evaluated are high-density fins, two different aluminium foams and compressed chips from the waste of aluminium machining. The sorption dynamic and cooling power density of each structure were measured through a Gravimetric Large Temperature Jump testing apparatus.
The results obtained showed that the best-performing configuration is the one with high-density fins, that, for a 90/30/20 °C cycle showed a Specific Cooling Power up to 1.1 kW/kg. The other structures exhibit a much slower adsorption process, corresponding to power densities of about 0.3 kW/kg. The results were used for sizing a full-scale adsorber, whose expected Volumetric Cooling Power is 500 kW/m3.