Thermoelectric water cooling

The following are some ways to cool water using thermoelectric cooler without ice formulation on the cold side of the thermoelectric module which acts as a thermal insulator:

- Using a direct cooling heat exchanger with a circulating pump with flow control to reduce residence time which may lead to ice formation and flow path blockage. A temperature sensor placed on heat exchanger output will be used to control the flow.

- Using thermoelectric module with magnetic stirring (see the proposed design below)

- Using swirling jets generated  by a small circulating pump

- Using more than one thermoelectric cooler with duty cycling (on and off control) to enable cold side deicing 

- Using stirring impeller

Thermoelectric cooler TEC1-12706

The following is just a schematic photo showing the size of thermoelectric cooler module TEC1-12706 .

Android stroboscope tachometer app concept

The following is a GUI concept for flash light stroboscope tachometer app which I think it is more easy and reliable than the design using scroll bars to control frequency. Each digit can be incremented and decremented separately.

Methods to detect magnet poles

The following are some methods to detect magnetic poles of a magnet:

- Hang a magnet with a string in area free of metals or magnetic fields. This method is not practical to implement.

- Using sizzling magnet on a flat horizontal glass surface as compass

- Using known magnet: this is the simplest way. If one magnet pole attract to the north pole of the known magnet, then it is the south pole and vise verse.

-  Using compass: the same as the previous method.

- Using electromagnet connected to DC power supply. When current passes through the coil, a magnetic field is generated and will have a magnetic field determined by right hand rule.

- Using clamp meter

- Using Cathode Ray Tube CRT screen (available in TV or oscilloscope): moving(1) electrons are deflected based on the direction of magnetic field(2) lines following Lorentz low (left hand rule). The direction of electrons movement is perpendicular to screen and pointing outward. Using MS Paint program, draw a horizontal line in the center of the canvas and display the image on full screen. Place the magnet parallel to the drawn line.  

- Using hall effect sensor.

- Using smart phone magnetic sensor: in my case, I am using Samsung Galaxy S3 mini. Just open the dial screen and write down the following secret code *#0*#, then press "Sensor" button. I claim that the location of the three-dimensional magnetic sensor is located at the center of the dial circle.

Counting number of semiconductor elements inside thermoelectric module

If you have a thermoelectric module (Peltier module) that you don't know how many semiconductor elements inside, all you have to do is to place it over a bright light source and count the elements. The following image shows the array of semiconductor elements (8 rows x 16 column).

Dual function Peltier water kettle (heating and cooling water on-request!!!)

I   It is a little bit imaginary, but it will be a dual function device. Save space of stand-alone water dispenser, get rid of water boiler, save energy, and save effort of changing water dispenser bottles.

Cooling: Give the right water temperature for the right person with this temperature adjustable water kettle. Get the water temperature you want on-request; just put the amount of water you want, adjust, and run. Don’t wait so long to get some cold water from a 1.5 L bottle just placed in the fridge, or from a 2 L water dispenser tank just filled from minutes.

Adjust water temperature for a person who is just coming from an extremely hot weather outside, for a person who have problems in his throat or teeth, for a child, … etc.

Heating: boil water or set water temperature accordingly if you prefer certain tea color and taste.

It may has two power options: AC power and DC power (in case of using it car). It can be made of glass with red and blue lights indicating mode (red: heating, blue: cooling). This idea is inspired somehow from the dry well temperature calibrators.

Exposed thermocouple junction | tip insulation

As we know, there are three types of thermo-couples according to junction type:

- Grounded junction

- Under-grounded junction

- Exposed junction

The following are some methods to electrical insulate exposed junction:

Using hot shrink tube:

A shrink tube of the correct size may be used to electrically insulate the exposed junction of thermocouple.

Using PVC insulation tape:
This is a very simple method but the PVC tape has low thermal conductivity.
Using beryllium oxide:
Source: http://www.instructables.com/answers/I-am-looking-for-a-material-that-is-thermally-cond/


The most thermally conductive electrical insulator is beryllium oxide.  It has the thermal conductivity of metallic aluminum and the electrical conductivity of aluminum oxide.  Insulating washers of this material are available to fit most bolt-down  transistor and diode cases, and this is the only practical way to use it, since BeO is a hard and very refractory ceramic.  Note that BeO dust is carcinogenic.  It's not hazardous in pieces too large to accidentally ingest, but don't even think of grinding a notch in a BeO insulator to fit an odd corner.

Thermal conductivity [W/m.K]
Dielectric strength [kV/mm]	330
Water resistance	Yes
Wear resistance	Yes
Maximum temperature (melting point)   [°C]	2507

Using motor | transformer winding enamel | insulation

Key words: wire enamel, insulation varnish

Thermal conductivity [W/m.K]
Dielectric strength [kV/mm]	3.3
Water resistance	No
Wear resistance	No
Maximum temperature [°C]

Using thermal conductive silicon pads

Using mica

Using diamond:

Diamond has the highest thermal conductivity on earth. Also, it has a very high hardness, so it is wear resisting. It can withstand high temperatures. For sure, diamond does not seem to be an economic solution in most cases.

Thermal conductivity [W/m.K]	2000
Dielectric strength [kV/mm]	1000
Water resistance	Yes
Wear resistance	Yes
Maximum temperature [°C]	Min. 3500

Using thermal conductive epoxy:

This method seems to be the most feasible and simple preparation method for relatively low temperature range. Thermal conductive epoxy is used in electronics field to seal components that are sensitive to water for water proofing like and in solid state electronic components like relays, diode bridges, and thermo-switches.

Epoxy pack is composed of two tubes (materials): one contains the resin and the other contains the catalyst.

The method is already used by Omega engineering for thermocouple types J, K, T, E (check the link below):
http://www.omega.com/pptst/TC-PVC_EPXOY_TC_PROBE.html

The highest thermal conductivity Omega provides provide is 0.712 W/m.K [model OT201]

3M adhesives (one of the leading companies in adhesives) also produces thermal-conductive epoxy with two options:
* 1-1.4 W/m.K [code TC2801]
* 0.72 W/m.K [code TC7207]

Thermal conductivity [W/m.K]	1.4
Dielectric strength [kV/mm]
Water resistance	Yes
Wear resistance	Yes
Maximum temperature [°C]

Refrigerator star rating

Each domestic refrigerator-freezer has what we call "Star rating". Star rating defines what is the storage temperature of the freezer compartment is. The lower the storage temperature temperature in freezer, the longest frozen food life is as the activity of micro-organisms is reduced. 

One star refrigerator-freezer has a storage temperature lower than or equal -6 C.

Two stars refrigerator-freezer has a storage temperature lower than or equal -12 C.

Three stars refrigerator-freezer has a storage temperature lower than or equal -18 C.

Four stars refrigerator-freezer has a storage temperature lower than or equal -18 C, but has a freezing capacity higher than 4.5 kg/100 L of the freezer's volume.

A question is: why freezers are rated using stars?!!!!

The answer simply is: it is inspired by the snow | ice flake shape under microscope which in most cases have the shape of the star.

Some funny facts about refrigerators

Nowadays, each house has one or more of these appliances:

- Food preservation appliances: refrigerators, refrigerator-freezers, chest freezers, and upright freezers
- Food preparation appliances: gas cookers, electric cookers, induction cook-tops, microwaves, and friers 
- Fabric care appliances: automatic washing machines, half-automatic washing machines, manual washing machines, driers, and electric iron
- Water care appliances: electric water heaters, gas water heaters, solar water heaters, water dispensers, water boilers
- Air care: air-conditioners, fans, and heaters
- Other



The following funny facts apply on refrigerators:

- Refrigerators are the most basic and high-priority appliances in each home
- Refrigerator is the only appliance that is connected to power source during the whole year
- The only appliance that is running for the whole year
- Refrigerators have wide variety of structures and layouts
- The most difficult appliance to dispose
- Normally, the longest appliance in home
- Also, the heaviest appliance in home
- The most difficult appliance to transfer.
- The most difficult appliance to repair with the available hand tools at home
- The most user-interacting appliance at home, this is why memos are stick to refrigerator doors!!!
- The only appliance you must run even if it is empty
- Refrigerator doors are the most mechanically-reliable doors in all appliances
- The only appliance you care about when electricity is cut off
- Number one appliance that can be used for built-in layout with door-on-door layout.
- Number one appliance that needs no utilities except for electricity.
- The most appliance that has been integrated with touch screens, and remote-control
- The only appliance that you can place large amount of staff on top of it!!!
- The first appliance to have lights inside it
- One of the most needed appliances for singles!!!

Blogger image white color test

In this post I show a bug in blogger image encoder. When uploading images with white color background, the white color is displayed as light grey for some image extensions. I tested these images on Google chrome and internet explorer and does not seem a problem of the browser.The following are some tests for different image extensions.