HYDRAULICS, PERFORMANCE AND COMFORT OF GROUND COUPLED HEATING-COOLING SYSTEMS

ABSTRACT The energy demand for heating is decreasing significantly in modern highly-insulated dwellings. Due to larger glass areas and well insulated buildings overheating becomes a problem. In a research project several hydraulic schemes with ground-coupled heat pumps and passive cooling with borehole heat exchanger have been evaluated. A parametric study with MATLAB/Simulink simulations using a residential low-energy building with floor heating system has been carried out. Simultaneous simulation of building and mechanical system showed dynamic interaction of floor and ground heat exchanger. Main objective is to estimate energy demand for heating and cooling, thermal comfort and economical feasibility of the overall system. A big challenge is appropriate control providing an optimal thermal comfort with a minimum of additional energy compared to heating only systems. Especially the meteorological conditions in spring and autumn cause intermittent heating and cooling which increases heating energy demand, since the concrete structure is alternately heated and cooled

Combining Heat Pumps with Solar Energy for Domestic Hot Water Production

AbstractIn a simulation study two combinations of air-to-water heat pumps with either solar thermal collectors or photovoltaics have been scrutinized. Other heating systems have been included in the comparison. All system components applied are field proven and available on the market. Although all heat generators were sized to cover space heating and domestic hot water demand, the focus lays on domestic hot water preparation. As required by local regulations, all systems cover 50% of the final energy demand from solar insolation. The results show that both air- to-water heat pump combinations are nearly equivalent regarding economic feasibility and environmental impact

Review of component models for the simulation of combined solar and heat pump heating systems

Combined solar and heat pump systems have a large potential to reduce CO2 and other emissions from the sector of domestic hot water preparation and space heating. Subtask C of the IEA SHC Task 44 / HPP Annex 38 deals with modeling and simulation of these systems. A review of component models for the simulation of combined solar and heat pump heating systems has been carried out with a special focus on the particularities of the combination of solar thermal collectors with heat pumps. Some of these particularities are effects of water vapor condensation on the surface of collector absorbers operated below the dew point, refrigeration cycles using more than one heat exchanger for the evaporator in order to use solar heat in addition to a conventional heat source, the effect of higher source temperature for the heat pump when solar heat is used, or the regeneration of ground heat sources with heat from solar collectors

Dysregulated iron metabolism in the choroid plexus in fragile X-associated tremor/ataxia syndrome

Fragile X-associated tremor/ataxia syndrome (FXTAS) is a late-onset neurodegenerative disorder associated with premutation alleles of the FMR1 gene that is characterized by progressive action tremor, gait ataxia, and cognitive decline. Recent studies of mitochondrial dysfunction in FXTAS have suggested that iron dysregulation may be one component of disease pathogenesis. We tested the hypothesis that iron dysregulation is part of the pathogenic process in FXTAS. We analyzed postmortem choroid plexus from FXTAS and control subjects, and found that in FXTAS iron accumulated in the stroma, transferrin levels were decreased in the epithelial cells, and transferrin receptor 1 distribution was shifted from the basolateral membrane (control) to a predominantly intracellular location (FXTAS). In addition, ferroportin and ceruloplasmin were markedly decreased within the epithelial cells. These alterations have implications not only for understanding the pathophysiology of FXTAS, but also for the development of new clinical treatments that may incorporate selective iron chelation