Italian researchers have discovered that combining residential air warmth pumps with air-geothermal warmth exchangers can scale back electrical energy consumption by as much as 30%. They examined the proposed mixture utilizing Matlab in a passive single-family constructing positioned in Valtellina, northern Italy.
Researchers on the University of Padova in Italy proposed to enhance the efficiency of residential air warmth pumps with air-geothermal warmth exchangers and located that this mix may scale back electrical energy consumption by as much as 30%.
The scientists investigated how the proposed mixture would carry out in a heating, air flow, and air-con (HVAC) system deployed in a passive single-family constructing positioned in Valtellina, northern Italy. The HVAC unit is described by the analysis group as an all-air kind unit that depends on a preheating/precooling air-geothermal warmth exchanger, warmth pump unit, and integrative post-heating thermal resistance.
“The objective of the examine is to research the habits of an air-geothermal warmth pump system to find out the principle elements that have an effect on the efficiency of the system below actual working circumstances and to find out will quantitatively scale back vitality consumption because of the integration of the air-geothermal warmth exchanger within the heating/cooling system,” mentioned the lecturers.
In the proposed system configuration, the air-geothermal warmth exchanger is used to pre-heat or pre-cool air relying on the climate. “This format ensures an virtually fixed temperature in the course of the heating and cooling intervals unbiased of the surface air temperature,” added the analysis group.
The warmth pump unit used within the experiment is a Compact P mannequin from the Danish producer Nilan supposed to work as an HVAC system and generator of home scorching water (DHW). Thermal resistance supplies heat throughout instances of excessive warmth demand. “The unit is designed to function in a standalone configuration, and due to this fact the air enter might be exterior air within the case of direct provide from the surface atmosphere or air pretreated within the air-geothermal exchanger,” emphasised the group.
During heating, the warmth pump is activated if the passive warmth restoration from the geothermal warmth exchanger will not be ample to make sure the specified consolation degree, or if the DHW demand is just too excessive. In the center of the season, the air pretreated by the air-geothermal warmth exchanger is handed to the warmth pump and the inlet air straight provides the inner atmosphere, with out warmth alternate. During the summer time, when the air provided by the warmth pump unit is just too scorching to satisfy the constructing’s cooling necessities, the compressor is activated and the air is cooled by the evaporator.
The system was modeled utilizing Matlab software program and was discovered to profit from the air-geothermal warmth exchanger, as it could possibly considerably scale back the heating and cooling demand in the course of the mannequin 12 months of operation, which in flip ends in 30% discount in energy consumption.
“From a quantitative perspective, the evaluation estimates that in winter 2019 with out the air geothermal unit, the electrical energy consumption will probably be 130% of the measured, because of the increased warmth demand, which in as a substitute results in the next operation of the post-heating electrical heater,” added the scientists. “In summer time 2019, the warmth pump didn’t meet the wants of cooling the home.”
They additionally emphasize that lowered indoor air flow, with low out of doors temperatures, is a significant factor in decreasing indoor warmth demand. “The outcomes affirm the affect of the air inlet circumstances and the management technique on the efficiency of the unit in heating and cooling modes,” they concluded.
The proposed mixture is described within the examine “Analysis of a home air warmth pump built-in with an air-geothermal warmth exchanger in actual working circumstances: The case examine of a single-family constructing,” printed in Energy and Buildings.
Another analysis group on the University of Padova offered final 12 months a 5 kW direct-expansion solar-assisted warmth pump that makes use of alternatively two completely different evaporator applied sciences. This system makes use of an air-finned coil warmth exchanger or photovoltaic-thermal (PVT) photo voltaic collectors because the evaporator.
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