Message from Daniel C. Thompson, Praecis CTO.

The Future of Temperature Control is Here:
The Next-Generation Temperature Control System

Praecis is proud to announce a new generation of temperature control systems that are environmentally benign, virtually silent, robust, maintenance-free, and capable of maintaining thermal stability to levels that until now were thought to be unobtainable or prohibitively expensive in a conventional laboratory or shop environment. The new Praecis Air Temperature Control System Solid State (ATCU-SS) series represents a merger of the old (the Peltier effect) and the new (Praecis' multi-loop control strategy and laminar flow air distribution system).

The Peltier effect has been known of for almost 200 years. Discovered in 1834 by the French physicist Jean-Charles-Athanase Peltier, the effect describes the cooling of one junction and the heating of the other when electric current is maintained in a circuit of material consisting of two dissimilar conductors or semiconductors. Until recently, applications of the effect have largely been reserved for spot cooling of small electrical components, and thermocouples for temperature measurement, where heating or cooling of a junction generates a current proportional to a change in temperature.

Two synergistic events have changed the course of Peltier technology applications: The semiconductor revolution, which has enabled the manufacture of Peltier wafers of ever-increasing dimension and cooling/heating capacity, and global warming, which is driving demand for heat pumps (air conditioners) that don’t rely on the phase change of a liquid refrigerant—a significant contributor to global warming. As manufacturers respond to increasing demand for Peltier-based heat pumps with larger and lower cost Peltier chips, Praecis plans to expand its ATCU-SS product line, and to reduce the cost of high-performance temperature control.

The new? We have merged the latest in commercially available Peltier technology with Praecis’ proprietary control and air distribution strategies, which include multiple loops of cascaded control with ultimate control dictated by a sensor (or sensors) located at the ‘critical point’ inside the subject enclosure, advanced ‘turbulators’ to ensure the thermal homogeneity of air entering the enclosure under control, and a passive air distribution system that delivers temperature-controlled air uniformly across the subject enclosure. The characteristic airflow, which, while inherently laminar, includes a micro-turbulent overlay, ensures optimal heat transfer without exposing the hardware under control to excessive aerodynamic forces.

The uniformity of the flow across the entirety of the enclosure also enables cost to be reduced; the air curtain along the walls intercepts heat transferred to or from the enclosure, thus obviating the need for insulation to protect the enclosure contents from conductive or convective heat transfer. Using a soft-walled enclosure is not only significantly less costly than one with insulated hard walls, it also gives us the opportunity to use clear PVC strip curtains, which effectively block radiative heat transfer, while providing easy access to the enclosure.

An example of Praecis’ first production version of its ATCU-SS series, an ATCU-SS 1200, was demonstrated at the ASPE 30th Annual Conference and Exhibition. Capable of controlling the temperature in a one square meter environment, we have included a test setup to demonstrate the dramatic part distortions that can result from a thermally unstable environment (the exhibition hall), vs. the dimensional stability provided in a temperature-controlled enclosure. Please feel free to drop by booth #104 for a demonstration and discussion.

Praecis Expands its Product Line to Include Humidity, Pressure, and Vibration Control, Multi-Enclosure Applications, and Turn-Key Cleanrooms.

The Covid-19 pandemic has produced at least some positive results. In Praecis’ case we took advantage of the breather to develop the ATCU-SS, and to develop solutions to problems that we have received inquiries about. In some instances, we developed our own solutions, in others we partnered with acknowledged experts. Our decision to partner was based on a fundamental observation: That organizations engaged in one cutting-edge technology are rarely equally successful in other cutting-edge applications.

Taking Praecis as an example, we like to think of ourselves as among the very best in the world of cost-effective, practical temperature control. Cleanliness control? We do well with purchased solutions for clean rooms. When it comes to cleanrooms ISO 5 and lower, however, we acknowledge that the special expertise required to accomplish and certify cleanliness control to the required levels is best left to the experts. Based on this observation, we have made a conscious decision to continue to focus on our core competencies, while being sufficiently knowledgeable of other environmental factors to implement solutions on our own, while knowing when to call in a partner. Praecis has forged collaborative agreements with:

A well-known manufacturer of state-of-the-art vibration control systems.
A local manufacturer of Cleanrooms down to ISO 0.

A European HVAC company that offers an isothermal humidity control system that can maintain relative humidity within +/-0.5%.

Finally, in response to numerous enquiries, Praecis has developed the capability to control the temperatures in multiple enclosures from a single ATCU, resulting in savings in cost and floor space. Unlike other systems, the new Praecis configuration is free from ‘cross-talk,’ whereby a perturbation in one enclosure (e.g., from opening the curtains) causes a disruption in the stability of other enclosures fed by the same ATCU.

Nov 1, 2021, Product Announcement.

Praecis announces its next-generation of temperature control.

The new Praecis Air Temperature Control System Solid State (ATCU-SS) series represents a merger of the old (the Peltier effect) and the new (Praecis' multi-loop control strategy, laminar flow air distribution system, and state of the art air mixing).

We have merged the latest in commercially available Peltier technology with Praecis’ proprietary control and air distribution strategies, which include multiple loops of cascaded control with ultimate control dictated by a sensor (or sensors) located at the ‘critical point’ inside the subject enclosure, advanced ‘turbulators’ to ensure the thermal homogeneity of air entering the enclosure under control, and a passive air distribution system that delivers temperature-controlled air uniformly across the enclosure.

The characteristic airflow, which, while inherently laminar, includes a micro-turbulent overlay, ensures optimal heat transfer without exposing the hardware under control to excessive aerodynamic forces. The uniformity of the flow across the entirety of the enclosure also enables cost to be reduced; the air curtain along the walls intercepts heat transferred to or from the enclosure, thus obviating the need for insulation to protect the enclosure contents from conductive or convective heat transfer.

An example of Praecis’ first production version of its ATCU-SS series. An ATCU-SS 1200, was demonstrated at the ASPE 30th Annual Conference and Exhibition. Controlling the temperature in a one square meter environment, we included a test setup to demonstrate the dramatic part distortions that can result from a thermally unstable environment (the exhibition hall) versus the dimensional stability provided in a temperature-controlled enclosure.