IJR highlights: latest R&D results regarding household refrigerators
The IIR estimates that the approximately 1.5 billion domestic refrigerators and freezers in operation worldwide consume almost 4% of global electricity1.
Even if the consumption of a typical household refrigerator dropped by around 65% within 15 years1, intense research and development continues to be carried out to further reduce it, as reflected by several recent articles in the International Journal of Refrigeration (IJR).
Articles in the IJR can be downloaded via the Fridoc database (link in the references below) or via the new IJR online service (free downloads, service reserved to IIR members).
- In their article2, Brazilian researchers stress that in 2012, for instance, refrigerators accounted for 18% of the Brazilian residential electric energy consumption.
They experimentally evaluated the thermodynamic behaviour of a typical domestic refrigerator insulated in 16 distinct ways with vacuum insulation panels (VIPs). They found that the energy consumption was affected by both the coverage area and the position of the panels. They also found that samples with the same coverage area presented distinct energy consumptions and vice-versa. The gathered data were correlated statistically in order to identify the most promising regions to install the panels. They observed that the energy consumption was reduced by approximately 6% and 11% when the doors and the rear wall are insulated with VIPs, respectively. They also found that a coverage area of 56% drops the energy consumption by 21%.
- In another article3, Turkish researchers have studied to what extent integration of two types of mini-channel condensers into a household refrigerator can increase the performance of the system.
Since the integration process requires the substitution of capillary tube which will be followed by charging a different amount of refrigerant, this work focuses on finding the right amount of the refrigerant and the right size of the capillary as well. This experimental study is carried out on a commercial household refrigerator in a climatic chamber. During the experiments, two types of mini-channel condensers have been analysed with five different capillary lengths and five varying coolant amounts in order to find the best combination for better performance. The outcomes of the study release the thresholds for either capillary length or refrigerant amount. The lowest energy consumption among investigated cases is obtained as 0.843?kWh/day by using a mini-channel heat exchanger with double intermediate plate, with a capillary length of 3.25?m and a refrigerant amount of 55?g. It leads to a 19% reduction of the energy consumption in comparison to the conventional system.
- Another article4 investigates the effect of a 10?mm phase-change material (PCM) layer mounted on the evaporator's surface on the energy performance and the heat transfer inside a conventional refrigerator. The impact of frost is also evaluated.
1 IIR, 29th Informatory Note on Refrigeration Technologies “The Role of Refrigeration in the Global Economy”, available following this link.
2 A study on the effectiveness of applying vacuum insulation panels insulation panels in domestic refrigerators, Thiessen S. et al, International Journal of refrigeration Vol. 96, Dec. 2018, p. 10-16: https://bit.ly/2MuNtlX
3 Integration of a mini-channel condenser into a household refrigerator with regard to accurate capillary tube length and refrigerant amount, Tosun M. et al, International Journal of refrigeration Vol. 98, Feb. 2019, p. 428-435, available following this link.
4 Characteristics and thickness effect of phase change material and frost on heat transfer and thermal performance of conventional refrigerator: Theoretical and experimental investigation, Berdja M. et al, International Journal of refrigeration Vol. 97, Jan. 2019, p. 108-123: https://bit.ly/2T9rILa