X-Message-Number: 17360 Subject: VPS pt 2 From: "Lionel Vogt" <> Date: Thu, 23 Aug 2001 10:58:14 -0400 The refrigeration units cooling ability is done through several solid state devices known as Peltier plates. The Peltier effect was first discovered in 1834. When current passes through the junction of two different types of conductors it results in a temperature change. Bismuth telluride is primarily used as the semiconductor material, heavily doped to create either an excess (n-type) or a deficiency (p-type) of electrons. They can be operated in a vacuum or weightless environments, and in any physical orientation. And are essentially heat pumps. Several of these units in a cascade configuration are mounted to a cylinder made of 6061-T6 aluminum. The peltier plates have a Hot side and a cold side, The hot side of the peltier has a heatsink mounted on it, A series of UHMW spacers support and outer shroud upon the cylinder that is used to guide air over the heatsinks and draw it away from the peltiers., cold side is mounted directly to the aluminum cylinder. Heat is pulled away from the units through the use of a high speed Fan commonly used for cooling computer equipment (120cfm) the surface of the aluminum cylinder is surrounded by a 1-inch thick polystyrene insulation. 2 internal liquid circulators are also mounted inside The cylinder as well.) Several temperature sensors, Some are mounted using open cell foam to make contact on the surface of the head. Others are to be slid into the sinuses and back of the throat. Next is a liquid heat exchanger that will be placed in the mouth and rest against the back of the throat and pallet, this will be supported by a pliable closed cell memory foam that is often used in the manufacture of earplugs. After being crushed to allow its placement into the mouth, it will expand and fill The mouth to create an airtight seal A neoprene rubber collar assembly seals to the cylinder with an water tight snap seal and locking ring The neoprene will seal around the person's neck, creating a watertight environment once his/her head is placed into the unit The same variety used in space helmets. The Refrigeration unit itself contains the entire temperature sensors and thermostat array The batterypack for the prototype at this time is using SLA type batteries (sealed lead acid) but they do conform to DOT standards and are allowed to be transported onto aircraft. The unit is a portable device with a carry handle and power supply/charger, Gauges on the unit allow for monitoring of power output and battery power remaining. The power supply can either convert voltages AC 110 to 220 to the 12 v needed to run the system, Or an onboard DC ? DC converter can be used with the correct adapter from 6V to 48V DC A lighter adapter can be used to plug it into any standard 12V DC outlet in a car or van during transport to extend battery life. After reaching sustained temperature, the present configuration of batteries allow for a runtime of 4 hours., Weight can be lost and runtime increased by converting to NiMh (nickel Metal Hydride) cells . However due to cost constraints of the prototype, SLAs will be used to prove the units Capabilities. The liquid precooler is much like the refrigeration unit. However this unit is smaller but contains the same number of Peltier plates as its larger brother. Its purpose is to cool a nontoxic, water soluble gel, only slightly thicker than water, the gel is designed to be cooled to below freezing while still remaining in its liquid state, a connecting hose and pump are also built into the unit that connects to a fitting on the Refrigeration unit Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=17360