As the energy efficiency of dishwashers continuously improves, differentmanufacturers need to find new innovative solutions to further improve thedishwashers. To do so one can divide the areas of improvement into 4 parameters,water temperature, washing time, chemical treatment and mechanical processing.In this thesis the focus lies on the mechanical processing and the washing time. The conventional spray arm of today's dishwashers sets its rotational velocitythrough the water pressure. To step away from this ASKO Appliances AB hasdeveloped a prototype with a motorized lower spray arm. The purpose of this studyis therefore to investigate how the motorized spray arm performs in terms of energyusage, wash results and sound. This when altering the factors water pressure,rotational velocity and washing time. To get reliable results with the least amount of tests, the methodology of Design ofExperiments was used through the software MODDE 7. A 3-level full factorialdesign was chosen. The three factors were varied in three levels -1, 0, 1 and fiveextra centerpoints were added resulting in a test schedule of 32 tests. To measurethe wash result a soiling method and an evaluation method was developed. Theresults of the executed test schedule was analysed through MODDEs in-builtregression model Multiple Linear Regression. The analysed test results showed that the wash time was the dominant factor forboth energy usage and wash result and the second most dominant factor was waterpressure. The rotational velocity had little to no effect on the energy usage and asmall effect on the wash result at a low water pressure but increasing effect for ahigher water pressure. The measured sound values were constant over time andincreased with both increased water pressure and rotational velocity. The optimalrunning conditions regarding wash result was investigated using MODDE and thentested. The optimal rotational velocity was the setting 1, the highest level, for allthree time settings. The optimal water pressure was in the mid to high region, andincreased with increasing wash time. The results from the three optimum tests for the prototype were then compared totests with a conventional dishwasher with a pressure driven spray arm. Theconventional dishwasher was runned with its normal running conditions for thethree different time settings. The prototype achieved a similar wash result as theconventional machine for the time setting -1 but slightly better for the time setting0 and 1. The energy usage for the prototype was a doubling of the conventionalmachines energy usage. The sound measurements were excluded due to muffelingdifferences between the machines
| Identifer | oai:union.ndltd.org:UPSALLA1/oai:DiVA.org:kau-85622 |
| Date | January 2021 |
| Creators | Karlsson, Karl-Johan |
| Publisher | Karlstads universitet, Institutionen för ingenjörs- och kemivetenskaper (from 2013) |
| Source Sets | DiVA Archive at Upsalla University |
| Language | English |
| Detected Language | English |
| Type | Student thesis, info:eu-repo/semantics/bachelorThesis, text |
| Format | application/pdf |
| Rights | info:eu-repo/semantics/openAccess |
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