Tuesday, June 25, 2024

Solar-assisted thermochemical warmth pump based mostly on caustic soda, water – pv journal International


Chinese researchers have designed a two-stage, solar-assisted thermochemical warmth pump system that makes use of caustic soda and water as a working pair. The system is reported to have the ability to obtain an power storage density of 363 kWh/m3 and is taken into account by its creators to be a super resolution for residential buildings with restricted house.

Researchers from Zhejiang University in China have designed a brand new solar-assisted thermochemical warmth pump system that can be utilized for house heating, cooling and home scorching water (DHW) in residential functions.

“In our work, we suggest a system that goals to realize larger power storage density,” the lead writer of the analysis, Guoqing He, mentioned. pv journal. “Using a thermochemical warmth pump permits us to make use of extra photo voltaic thermal power and scale back the necessity for electrical energy.”

The foremost characteristic of the system is that it depends on a working pair fashioned by sodium hydroxide (NaOH), often known as caustic soda, and water. According to the analysis crew, the NaOH/water pair has benefits equivalent to low worth, excessive warmth switch coefficient, excessive power density, brief restoration time, and compatibility with the storage temperature of standard collectors. in solar-thermal. “We present that this technique can work with a focus distinction of 70% wt and 30% wt, respectively, for the local weather of scorching summer season and chilly winter areas in China,” he added. he.

The system consists of two NaOH reactors, two warmth exchangers, 4 tanks, and solar-thermal collectors. defined the teachers, saying that the NaOH reactors work respectively as a condenser or an evaporator. “The resolution takes on water vapor and turns into diluted, releasing the absorbed warmth together with its saved chemical power for heating. In the charging course of, the solar’s warmth is used to reform the answer by desorbing the vapor from the answer. The resolution might be concentrated once more and thus get better the potential to extract warmth from the low temperature supply for heating within the subsequent cycle.

The scientists simulated the efficiency of the warmth pump system assuming that it’s utilized in a household home with a ground space of ​​220 m.2 in Hangzhou, China. The anticipated annual whole heating demand is 11,650 kWh, together with winter house heating of 8072 kWh, winter DHW of 1298 kWh, and summer season DHW of 2280 kWh.

“During the non-heating interval, the photo voltaic thermal collectors cost the answer and keep it at a excessive temperature till the beginning of the heating interval,” they mentioned, describing the operation of the sytem. “Then, the answer acts as a warmth pump, which takes the warmth from the low temperature supply and delivers it to the constructing, together with the photo voltaic heating from the collectors and the saved smart warmth of the answer. The resolution turns into chilly and diluted on the finish of the heating interval, and is able to be charged once more.

The evaluation reveals that the system can obtain an power storage density of 363 kWh/m3. The group additionally discovered that the warmth pump needs to be 35.13 m2 of photo voltaic collectors and 32.47 m3 in storage tanks. “Compared to affordable seasonal storage, the collector space is diminished by 12.5% ​​and the cupboard space is diminished by 59%, with attainable additional discount by means of optimization,” they mentioned, emphasizing that the proposed system is a sound resolution for residential buildings with restricted house. “Collectors sized for discharging the answer throughout non-heating intervals may produce extra photo voltaic warmth for winter heating.”

The analysis crew additionally emphasised that the preliminary funding for the system should still characterize a problem to beat for its industrial maturity. “Our warmth pump is properly fitted to integrating PV in most climates,” he mentioned. “However, the preliminary prices can nonetheless be very excessive.”

Looking forward, the researchers say they need to do a extra detailed dynamic simulation. Their findings are contained within the paper “Two-Stage Solar-NaOH Thermochemical Heat Pump Heating System for Building Heating: Operations Strategies and Theoretical Performance,” which was just lately revealed in FORCE.

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