Automated system for testing washers, dryers and dishwashers Theseus Lab

Project title

Workstation for washing machines and dishwashers testing.

Project execution time

Project start: 11/11/2014, Project completion date: 29/07/2016

Customer

Belarusian State Institute for Standardization and Certification

PROJECT GOALS
AND OBJECTIVES

The workstation is designed for testing washing machines and dishwashers in accordance with the requirements of IEC 60456.

The equipment can be used in the following cases:

  • in measuring and certification laboratories and centers;
  • during mass production and control of washing machines and dishwashers;
  • during the prototypes development of washing machines and dishwashers.

The Belarusian State Institute for Standardization and Certification got the opportunity of testing energy efficiency of washing machines and dishwashers with the possibility of water preparation according to the method B of EN 60734.

PROJECT TECHNICAL
DESCRIPTION

The workstation consists of a water treatment system and a set of measuring equipment for checking the parameters of water and materials used in washing machines and dishwashers testing.

The water treatment system prepares water in accordance with the requirements of EN 60734 Method B. The prepared water accumulates in storage tanks with a capacity of 1000 liters for later use in testing.

The water treatment system consists of several units:

  • pre-treatment and osmosis unit,
  • water cooling units,
  • water heating block,
  • chemical mixing and dispensing unit,
  • accumulation units,
  • high-pressure units to ensure constant water pressure during testing,
  • control unit.

The water treatment system is connected directly to the water supply and can operate autonomously in the 24/7 mode.

Prepared water can be fed to washing machines and dishwashers by two pipes each with its own temperature.  The outlet water temperature can be set on the control unit in the range of 5 to 60°C.

During the test, periodic water monitoring is required. In some cases, the control of water parameters and reference materials should also be performed after the tests. For example, measurements of the reference materials parameters should be carried out after the end of washing while testing washing machines.

The water treatment system is powered by three-phase network 400V 50 Hz. Power consumption is not more than 40 kVA.

A fully automated workstation allows performing all measurements of the energy efficiency of washing machines and dishwashers in automatic mode and generates reports and protocols in accordance with the selected test program.

The software for the control unit is written in LabView and has many user-friendly features to manage, control and monitoring of water parameters.

OPERATING
PRINCIPLE

Operation of the system includes the following stages. 

Stage 1. Demineralization of tap water.

This process is designed for cleaning tap water and obtaining demineralized water by reverse osmosis.

  1. Tap water is fed into the reverse osmosis system directly from the central water pipe using a connecting hose.
  2. Water passes through the necessary filters (coarse filters, fine filters, etc.) and then subjected to a reverse osmosis process.
  3. Osmosis purified water accumulates in a storage tank (ST1) for further mineralization.
  4. There is a conductivity sensor C in ST1, which constantly checks the water after osmosis for compliance with the following parameters: water conductivity less than 10 mkS/cm.
  5. If the water parameters do not meet the standards, it pours into the sewerage system. After this, it is necessary to clean and/or replace the filters in the osmosis system.
  6. After filling the ST1 with water and obtaining water parameters that meet the requirements of standards, the system switches off the osmosis process automatically.
  7. If the concentrates preparation was carried out in parallel with osmosis, then the operator can manually start the mineralization process.
  8. The system allows restarting the osmosis process (manually or automatically) at depletion of demineralized water. ST1 has a minimum water level sensor, which gives the command to activate the osmosis process and refill ST1.

Stage 2. Preparation of salt concentrates.

This process is designed to prepare three salt concentrates in accordance with the requirements of standards, as well as to check the sufficient amount of salts and alkalis in the tanks for pH and conductivity control. The preparation process can begin in parallel with demineralization, osmosis or immediately after its termination.

  1. A special scale is used to weigh the exact amount of each salt, based on the volume of the tank for concentrate storing (CT).
  2. Measured quantities of salts are poured into the appropriate CT.
  3. Further, these CT are filled with demineralized water up to the volume for which the salt was measured.
  4. After that, the tanks are closed. All CT have minimal air access to minimize reacting with air and precipitate.
  5. Further, the operator manually starts the process of regular mixing of solutions in each CT. For this purpose, each CT has a stirring mechanism to continuously maintain the homogeneity of the concentrate (automatic stirrer with adjustable on / off period).
  6. It is allowed to prepare the concentrate of each salt not directly in CT, but in a separate container.
  7. Simultaneously, the user checks whether the amount of NaCl / Na2SO4 and alkali NaOH and HCl acids is sufficient in the tanks for adjusting the pH and conductivity C (SB_pH +, SB_pH-, SB_C +). If necessary, user can add salt/alkali from standard purchased containers.

Stage 3. Water preparation according to the standards.

The objective of this process is the complete preparation of water in accordance with the requirements of the standards.

  1. After preparation of all concentrates, the operator manually starts the process of water mineralization. Water from ST1 is influent (1 liter) into ST2 (storage tank for fully prepared water). In accordance with the requirements of the standard, doses of each of the three salts (NaHCO3, MgSO4 ∙ 7H2O, CaCl2 ∙ 2H2O) are added to the water in parallel or serial mode. The system allows to program the doses of each salt directly on the dispenser or on the central control panel.
  2. The mineralization process automatically stops after filling ST2 (1 m3).
  3. At this stage, the thermostating process is activated (using a thermostat). The system brings the entire volume of mineralized water to the desired temperature (15, 20, 60 degrees).
  4. The system automatically switches on the pH sensor located in the ST2 after reaching the required and homogeneous temperature throughout the water volume. The pH sensor measures the hardness of the water.  The system notifies about the compliance of the water hardness level with the requirements of the standard. If the water hardness level differs from the standard values, the system sends a command to one of two dispensers connected to tanks with HCl acid or NaOH alkali. Depending on the PH level, the running dispenser adds a certain amount of acid or alkali into ST2. At the same time, mixing and thermostating of the entire volume of water in ST2 continues. After a certain time (can be adjusted manually), the pH sensor again measures parameters and, if necessary, repeats the pouring of next dose.
  5. After reaching the required pH, the system automatically switches on the sensor C (conductivity sensor) located in ST2. Sensor C measures the conductivity of water. The system notifies about the compliance of the conductivity level with the requirements of the standard. If the conductivity level differs from the standard requirements, the system sends a command to the dispenser connected to the container with NaCl/Na2SO4 salt. Depending on the PH level, the running dispenser adds a certain amount of salt into the ST2. At the same time, mixing and thermostating of the entire volume of water in ST2 continues. After a certain time (can be adjusted manually), the pH sensor again measures the parameters and, if necessary, repeats the pouring of next dose.
  6. The system signals the completion of the water preparation process and the readiness of water for use after receiving the appropriate commands from three sensors (t, pH, C) indicating that all measured water parameters correspond to the standard.

Stage 4. Maintaining stable water parameters for 1 day.

The objective of this process is to maintain the correct water temperature throughout the test cycle (according to EN 60456 for one day).

SYSTEM
SPECIFICATIONS
Output water parameters
PARAMETER VALUE
Water temperature 15 ± 2, 20 ± 2, 60 ± 2°С
Hardness of water 2,5 ± 0,2 mmol/l
Water outlet pressure 240 ± 20 kPa
Performance 5 m3 in a week
рН measurement range 0,00 ÷ 14,00
Conductivity measurement range 0 ÷ 20000 μSm/cm
Operating mode round-the-clock
WORKSTATION
STRUCTURE
DESCRIPTION
Water treatment system
PH meter
Automatic titrator
Water conductivity meter
Manual titrator
Anemometer
Volumetric ware for dosing
Consumable products (chemicals)
Personal computer
Desk, operator’s chair
RELATED
STANDARDS
SHORT DESIGNATION FULL TITLE
IEC 60456 Clothes washing machines for household use – Methods for measuring the performance
STB EN 60456-2013 Automatic electric washing machines for household use. Methods of performance measurements.
GOST R IEC 60456-2011 Air conditioners, liquid cooling units and heat pumps with electric compressors for heating and cooling of the premises – Part 3: Test methods
BS EN 60734:2012 Household electrical appliances. Performance. Water for testing
EN 60734 Household electrical appliances – Performance – Water for testing

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