Problem Identification for Product Development Opportunities of Wine Refrigerators

University essay from KTH/Energiteknik; KTH/Energiteknik

Author: Malin Maria Erlandsson; Petra Näsström; [2018]

Keywords: ;

Abstract: Both value and flavor of wines can improve with time if stored properly. The factors with the most profound effect on the wine are light, humidity, temperature, vibrations, and ventilation. Light consisting of shorter wavelengths, under 450 nm, are dangerous for wine and can destroy the structure in wine. The humidity is supposed to be kept between 50-80 %, mainly to prevent the wine cork from drying out, since this would result in a shrinkage that will let in air to the bottle. When considering temperature, the ideal maturing temperature is 12-14 °C for both reds and whites. It is also essential to keep the wine at a stable temperature; it should not fluctuate more than 1.5 °C per day or 2-3 °C over a year. Larger amplitudes of vibrations cause an increased structural change in wine molecules. Therefore, they should be kept as small as possible. Ventilation is required since a reasonably small closed space with high humidity leads to a mold-prone environment which could be devastating to the wine.  The wine market is shifting from bulk wine to becoming more wine enthusiast focus where it is believed the importance of a wine refrigerator will increase with this shift.  The wine business is not scientifically originated. Several requirements are mainly “hearsay” and “common knowledge”. The aim of this paper was to identify scientifically founded facts to product develop wine refrigerators for a global market.  Four different wine refrigerators called A, B, C, and D, from different brands, were tested in a laboratory from a wine requirement perspective with a focus on temperature, humidity, and electricity consumption. All tests were conducted for 24 hours. Both temperature and humidity were logged every 10 seconds and results were processed in MATLAB and presented in graphs. It was found that cabinets with separators held a more accurate temperature than those without one. It was also found that most of them held a temperature within the allowed fluctuation interval. Moreover, the air temperature fluctuation did not significantly affect the temperature inside the wine bottle indicating it is not important to further improve. The humidity was tested both with and without load but did not give a significant difference, which indicates the cabinets does not have a unique system to add humidity to the cabinet. Overall, all cabinets except one reached an average of at least 50 % relative humidity, which is the minimum requirement. The functionality of the humidity system of each unit is in question.  Most surprisingly, the high electricity consumption for all of the wine fridges entails potential improvement area of the cooling system that uses more energy than what is thought to be needed. A comparison with a regular domestic refrigerator shows great potential for improvement, especially since a wine fridge only needs to perform a temperature of 12 °C, while a domestic fridge keeps a temperature of approximately 4 °C. The vast amount of energy use could also be because of inadequate insulation, with leakage through or around the glass door. A closer look at the gaskets showed small unsealed spots where the gasket was not tightly against the cabinet, enabling ambient air to leak in. Overall, the energy consumption results highlighted an inefficient cooling cycle.  The found development opportunity is to include a variable-speed compressor into the refrigeration unit to maintain proper internal climate regarding temperature, humidity, and energy demand. Furthermore, the results of this thesis highlight the light blockage solutions which seem non-considered in the tested refrigerators and what was found in the market. 

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