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Study on heating and energy storage for multi-split air source heat pump unit. • Indoor units affected frosting, heating and energy storage performances notably. • Optimal time of energy storage operation was around 10 min after the heating. • Energy storage decreased the average heating capacity and COP by 4.4% and 1.9%.
With the wide applications of thermal energy storage (TES) to HVAC systems, a TES based reverse cycle defrosting method has been developed [25], [26], and the experimental results showed that this TES based defrosting method could provide adequate heat for defrosting, leading to a shortened defrosting period, an increased
1. Introduction. Air-source heat pumps (ASHP) are widely used in heating applications because they are environmentally friendly, energy-efficient, and two to three times more efficient than traditional gas and electric water heaters [1], [2], [3].However, in low-temperature environments, air-source heat pumps are accompanied by increased
working conditions of cold storage air cooler, that is, the evaporation temperature of cold storage is -30℃, the air inlet temperature of cold air cooler is -18℃, the relative humidity in the cold storage is 60%, and the air inlet velocity is 3m/s. It is calculated that after four hours of cumulative operation of the compressor, the frost
To solve the fundamental problem of insufficient heat available during defrosting while ensuring the efficient and safe system operation for air-source heat pumps (ASHPs). A novel reverse-cycle defrosting (NRCD) method based on thermal energy storage to eliminate frost off the outdoor coil surface was developed. Comparative
A novel hot-gas bypass defrosting method for an air source heat pump (ASHP) unit has been presented in a previous work, which can satisfy defrosting and
To solve the fundamental problem of insufficient heat available during defrosting while ensuring the efficient and safe system operation, a novel reverse cycle defrosting (NRCD) method which is thermal energy storage-based using sub-cooling energy of refrigerant for ASHPs has been developed.
The experimental results showed that the multi-ASHP unit employing fin-tube energy accumulator with serial energy storage method can achieve the longest heating period, which was 3.3%, 13.4%, and
In addition, a single storage unit with a storage capacity around 100 kWh can meet a 16-h heating demand of space heating with a base heating load of 30 W m⁻² and a minimum heating temperature
Experimental study on the melted frost influence on the metal energy storage during an air source heat pump defrosting. Author links open overlay panel Mengjie SONG a, Ning MAO b. Show more As seen, when the melted frost was taking away during defrosting by water collecting trays, in Cases 3 and 4, the temperature of
Request PDF | Operating performance of novel reverse-cycle defrosting method based on thermal energy storage for air source heat pump | To solve the fundamental problem of insufficient heat
Thermal energy storage (TES) based reverse cycle defrosting method has been proposed to solve the defrosting problem for cascade air source heat pumps (CASHPs), with the benefits of shortening
This paper proposes a solar-air source energy storage heating system (SASES-HS), which can solve the problems of high energy consumption and difficult defrosting when the ambient temperature is
Frost deposits on the outdoor heat exchanger of an air source heat pump (ASHP) air conditioner and reduces its capacity during winter operation. However, the prevailing reverse-cycle defrosting (RCD)
Energy flow chart of the air source heat pump with thermal energy storage defrosting. Based on the above operating principles, governing equations of this system can be expressed as below. Energy equation in heat storage mode is (1) Q e1 + f comp P 1 = Q c1 + Q s1 where f comp represents heat loss factor of the compressor.
Experimental results show that, the heating supply of indoor air thermal energy contributed about 80% of the total energy usage for defrosting, nearly 90% of energy consumed on frost melting and
It can be seen that the PCM-HE is a key component to the successful development of the novel defrosting method. To obtain the highest possible defrosting efficiency, firstly, the storage capacity of the PCM should be determined based on the frequency of defrost cycle, outdoor air temperature and humidity, the capacity of an
The air source heat pump integrated with a water storage tank prevents frequent shutdowns and startups of ASHP units, and reduces indoor temperature
To solve the fundamental problem of insufficient heat available during defrosting while ensuring the efficient and safe system operation, a novel reverse cycle
Hence, an energy storage air-type solar collector was developed. The schematic of the solar collector is shown in Fig. 1. The designed solar collector uses air as the heat transfer medium, which prevents vacuum tube blockage during winter and the pollution and corrosion caused by leakage of the filling liquid.
To solve the fundamental problem of insufficient heat available during defrosting while ensuring the efficient and safe system operation for air-source heat
For example, for an air source heat pump unit operating in frosting/heating mode, compressor shutdown defrosting, electric heating defrosting, hot water spray defrosting, hot gas bypass defrosting
Experimental results show that the proposed method reduces total defrosting energy consumption by 27.9% comparing with the RCD method. It also
The research results showed that indoor air provided 78.1% of the defrosting energy, and 59.4% of the supplied energy was used for melting the frost. Song et al. (2017) studied the effect of metal energy storage on defrosting by changing the size of outdoor coil. When the outdoor coil increased by 50%, the energy consumption of the
(in Chinese) [10] Dong Jiankai, Jiang Yiqiang, and Yao Yang. “Experimental study on the characteristics of thermal energy storage for air-source heat pump defrosting using sub-cooling energy of refrigeration.†Acta Solar Sinica, 33 (9) (2012): 1536-1540.
Thus, the temperature fluctuation of supply water during the defrosting process was reduced by 69 %. In addition, the cumulative COP of Air Heat Absorption Defrosting method was 9.3 % higher than reverse cycle defrosting method, which could be attributed to the fact that the defrosting energy mainly came from air heat absorption.
During the defrosting process in cold regions, the air source heat pump with vapor injection encounters some problems, e.g. long defrosting time and low
1. Introduction. In recent years, the use of fossil energy and its environmental problems have attracted great attention all over the world [1].According to a report from the International Energy Agency in 2021, the world total final electricity and natural gas consumption accounted for 19.7% and 16.4%, respectively, of the world final
the defrosting duration, improve the indoor thermal comfort, and reduce the defrosting energy consumption in defrosting. Key words: air source heat pump; thermal energy storage; phase change material; reverse-cycle defrosting 1 Introduction Being energy-saving and environmentally friendly, air-source heat pumps (ASHPs) have been widely
Compared with other defrosting technologies, in addition to raising the compressor''s suction and exhaust pressures, heat storage defrosting can also strengthen the system''s stability. When defrosting ASHPS, the issue of energy supply and demand contradiction can be resolved through the application of heat storage defrosting
Hot water spraying defrosting (HWSD) used in large and medium-sized cold storage uses a water spray device to spray hot water on the outer surface of the evaporator [13]. Comparison between hot-gas bypass defrosting and reverse-cycle defrosting methods on an air-to-water heat pump. Appl. Energy (2009) J. Dong et al.
Metal energy storage (MES) had a negative impact of −7.5 % on defrosting efficiency due to a large amount of energy required to heat MCHX. Moreover, the negative influence of frost melt water and retained water on defrosting efficiency was −9.5 % and −1.9 %, respectively.
To solve this problem, a novel frost-free air-source heat pump water heater (ASHPWH) system has been developed, which coupled with an extra heat exchanger coated by a solid desiccant (EHECSD) with an energy storage device (ESD).
Zhang et al. [21] developed a no frost heat pump water heater coupled with solid desiccant, in which frosting on the outdoor coils can be prevented by dehumidifying the entering air in the heat pump water heater. The simulation results indicated that the average COP of the system is improved by 5–30% than using the hot
To solve this problem, a novel frost-free air-source heat pump water heater (ASHPWH) system has been developed, which coupled with an extra heat exchanger coated by a solid desiccant (EHECSD) with an energy storage device (ESD). J., 2015. "Evaluation of defrosting methods for air-to-air heat/energy exchangers on energy
The negative effect of metal energy storage on defrosting efficiency is −7.5 %. heating retained water, and (6) heating ambient air. Obviously, the energy consumption of melting frost was 325.5 kJ, accounting for 33.7 % of the total energy, which was the largest proportion. The energy consumption of vaporizing water was 127.3 kJ
Thus, the temperature fluctuation of supply water during the defrosting process was reduced by 69 %. In addition, the cumulative COP of Air Heat Absorption Defrosting method was 9.3 % higher than reverse cycle defrosting method, which could be attributed to the fact that the defrosting energy mainly came from air heat absorption.
Qu et al. [22] investigated the operating performance of the cascade ASHP system with a thermal energy storage based heat exchanger, and suggested that the stored thermal energy could provide for
Data reduction The electrical energy consumption, Wd, during a defrosting period, td, was evaluated by:  Î"== tPPdtW dt d 0 (1) where P is the input power to the prototype CASHP unit during a defrosting operation, W The heating capacity for the HT cycle, qHT, can be evaluated by: )(HT inoutaaa ttcGq âˆ''= Ï (2) where Ga is
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