FOOD COOKING MEDICAL STERILIZATION

and ICE MAKING (adsorption process) with the "SOLEIL-VAPEUR" SOLAR THERMAL STEAM UNIT

100 - 164 °C / 0 to 6 bar / 0.5 to 10 kW

The "soleil-vapeur" Solar-Thermal Steam Unit has been designed to be used in areas wherea good direct solar flux is available and where traditional sources of energy are restricted andexpensive.

Operated manually this rugged equipment is not connected to power supply nor features anyautomation.

The Solar Thermal Steam Unit is targeted for professional or collective use, not individual or family use.

This document is a brief presentation of the Solar-Thermal Steam Unit (I) and three possibleapplications (II).

I – THE SOLAR THERMAL STEAM UNIT 1- Frame (square steel tubes)

2- Semi-parabolic trough mirror oriented Est-West

3- R. Winston Compound Parabolic Concentrator

4- Manual aiming system

5- Manual feed pump

6- Linear boiler (steel pipe installed inside the CPC)

7- Steam exhaust tube

8- Insulated vessel, for cooking or sterilization

9- Storage box for mirrors

The 2 m² mirror unit (pictured) is the smallest possible dimension, thelargest dimension being 16 to 20 m². Several units can be coupled inparallel. In this condition, the efficiency is more than proportional to themirror surface, due to the scale effect inherent in thermal machines. Thesun/steam efficiency is 33 % for a 2 m² unit and exceeds 50 % for a 16 m²unit.

soleil-vapeur.org Oct 2014 page 1 /4

1

2

3

54

6

7 8

9

II- APPLICATIONS FOR THE STEAM

this section describes three applications : (1) food cooking ; (2) medicalequipment sterilization , and (3) ice making.

II-1) Food cooking with the steam hot plate

The solar-thermal steam unit can easily boil or steam cook under atmosphericpressure a variety of foods such as vegetables, meat, rice, etc….In addition to cooking, the unit can be used for agro-food processing: dairy,slaughter, semolina processing, brewery, essential oil distillery, bio fuel(processed from Jatrofa Curca or other) …

A cooking pot is placed on an aluminium hotplate which, fed with the steam from the unit, operates like an electric hot plate. In order to minimize thermal loss, the hot plate and pot are placed inside an insulated box.

With a 2 m² unit under a direct solar flux of 900 to 950 Watt/m²:- One can boil or steam cook (atmospheric pressure) three to four 4 kg vegetable loads per day,

- A 2m2 unit (as shown above) takes 10-15 mn to bring an additional liter of water back to boilingconditions.

- The power available to the user is 500 watts in terms of steam circulating through the hot plateinside the insulation box, during six hours per day (from 9 a.m. to 3 p.m., local solar time).Depending on the size of the unit, it is possible to use several steam plates.

The steam plate has been engineered and developed by Rice University, Houston, Texas, USA.

Page 2/4 Oct 2014 soleil-vapeur.org

4 kg of cooked potatoes

Why use a thermal fluid? The solar energy flux is diluted, with an approximate maximum of1000 W/m². In order to have enough energy, it must be collected on a large surface andtransferred to the utilization point by means of a thermal fluid. Furthermore, with energybeing brought to the core of the cooking device, this device can be insulated.

II-2) Medical equipment sterilization with the steam hot plate

Steam wet sterilization is the best means of sterilisation for most medical instruments. It isone in the array of tools used against a variety of bacteria and viruses, including HIV/AIDS.A standard medical steriliser (autoclave) such as the wafco.com ones (14 or 24 litres gross capacity)can be used. Given the level of steam temperature provided by the solar -thermal steam unit (maximum 164 °C), the registered temperature of 121° C can be maintained for 30 mn or 134 °C for 18 mn to achieve effective sterilization.

Under a 900 W/m² direct flux, a small 2 m² unit can carry out three daily sterilisation sessions with a 14 or 24 litres sterilizer.

Except the fact that the thermalpower is supplied by steam instead of electricity, the operation of the steriliser is identical to the usual operation of N type medical sterilisers.

The steam supplied by the unit used as thermal fluid toheat the hot plate never comes into contact with thesterilisation steam produced inside the sterilizer.

The complete installation has been successfully tested using indicator tapes and successfully checked usingbiological agent kits through 27 consecutive tests atRice University in Houston, Texas, USA in 2011. Results are reported in the article "Validation of theEfficacy of a Solar-Thermal Powered AutoclaveSystem for Off-Grid Medical Instrument WetSterilization" published by The American Journal ofTropical Medicine and Hygiene, http://www.ajtmh.org/content/87/4/602.abstract

Further information can be found on the web using keywords: "rice university capteur soleil sterilisation".

soleil-vapeur.org Oct 2014 page 3/4

And why use steam? Several kinds of fluids could be used. All in all, steam presents moreadvantages than others, in spite of some drawbacks that can be annoying for the beginner.Steam is the most used fluid worldwide, producing almost all electrical power.

II-3) Ice making via adsorption

An ice production machine (adsorption process with zeolite) has been built. This machine usesthermal power, unlike nearly all frigorific systems that use mechanical power.

1 -Evaporator

2 – Zeolite reactor

3 - Condenser

4 - Vacuum circuit (not shown)

5 - Evaporator – reactor piping

6 - Reactor – condenser piping

7 - Insulated container

8 - Heating supply, not shown (steam from Solar-Thermal Unit)

9 - Coolant supply, not shown (water from a water tank)

During the first runs of the prototype (2014), the ice production per cycle is between the 2/3 and the3/4 of the zeolite weight.

The work relative to the Thermal Steam Unit originally took place within the scope of a small association with a few people from Brest area in France. The work was paced by meeting skilled people and by availability of funds, most of it being private funds. Hence there were more active times (first production of steam in 1995, patenting the optical arrangement of the collector in 1996 in France, steam hot plate in 2010, medical sterilisation in 2011 at Rice University in Houston Texas USA, ice machine in 2014) and less active times.

Today, this saga is not finished and there are a few more chapters to write about useful applications fo the Solar Thermal Steam Unit.

This document can be downloaded from www. soleil-vapeur.org Oct 2014 Page 4/4

About soleil-vapeur.org