A computer cooling system has a mixing valve which supplies coolant to the computer and receives hot return coolant from the computer and also chilled return coolant from a chiller intermediate the computer and the mixing valve. The mixing valve mixes the hot return coolant with the chilled return coolant to adjust the cooling system temperature. Control circuitry senses, or estimates, the dew point temperature of the computer room environment, compares it with the cooling system temperature, and adjusts the mixing valve to maintain the cooling system temperature a few degrees above the dew point temperature. A condensation sensor comprises of a light emitting diode (LED), reflective tape applied about a cooling system supply conduit, and a phototransistor is disclosed. Light from the LED is fully reflected by the reflective tape to the phototransistor in dry conditions, but only partially reflected when condensation forms on the tape. The phototransistor output drops when condensation impedes the reflectability of the tape resulting in only partial reflection of the light and this drop in the phototransistor output is sensed by circuitry associated therewith to shut down the coolant pump and the computer system.

Dew point sensitive computer cooling system

According to certain embodiments disclosed in the present application, a climate controlled seating assembly includes a thermal module. The thermal module comprises at least one inlet channel, at least one outlet channel and a thermoelectric device (e.g., Peltier circuit) positioned upstream of the outlet channel. In one embodiment, the seating assembly includes a sensor positioned within an interior of the thermal module and configured to detect the presence of a liquid, such as water, condensation or other fluids, on or near said sensor. In certain arrangements, the sensor is configured to detect the presence of a liquid by measuring an electrical resistance or capacitance across a portion of the sensor. A climate control system can include a separator gasket located within a housing of a fluid module and at least partially between the cold passage and the hot passage. In some embodiments, the separator gasket comprises one or more wicking materials. The separator gasket can be configured to transport liquids from the cold passage to the hot passage.

Condensation and humidity sensors for thermoelectric devices

A control for controlling a multi-zone HVAC system, wherein the heating or cooling equipment is operable in multiple stages, takes the demand on the system over time into account when determining an appropriate stage. In particular, a time integral of the system demands is utilized along with a current system demand to determine an appropriate stage. In this manner, a weakness in the prior art of allowing a long-term, small difference between the desired set point and the actual temperature in the various zones is addressed.

Control of multi-zone and multi-stage hvac system

A thermoelectric system which comprises two substrates spaced apart from each other to form a gap and a plurality of electrically-connected semiconductor elements disposed between the substrates in the gap. The thermoelectric system further comprises at least one sensor and a seal which extends between the substrates and encloses the sensor and at least one of the plurality of semiconductor elements. The sensor is disposed between the substrates at an interior location spaced from the peripheral edge of at least one of the substrates. Additionally, at least one of the semiconductor elements is disposed between the sensor and the peripheral edge.

Thermoelectric device with internal sensor

An instrument measures the LED junction temperature directly by taking advantage of the linear relationship between the forward current driven through the LED, the forward drop of the LED, and the junction temperature to determine the LED junction temperature Calibration is conducted by placing two LEDs from the same family in ambient temperature and passing a small test current through each of the LEDs to obtain the forward drop of the LED at ambient temperature The LED under test is then placed in an environmentally-controlled chamber where the temperature is raised a known amount above ambient temperature Known low and high voltage values are associated with the ambient temperature and the environmental chamber temperature, causing the LED under test becomes a calibrated thermometer that can measure its own junction temperature due to the linear relationship between the forward drop and the junction temperature

LED junction temperature tester

Apparatus for measuring relative humidity within a given environment includes first and second operational amplifiers connected in a positive feedback loop. The first amplifier supplies an input signal to the second amplifier enabling the second amplifier to provide an amplified output signal which is fed back to an input of the first amplifier. First and second thermistors, which sense dewpoint and ambient temperatures, respectively, within the environment, control the gain of the second amplifier in accordance with changes in relative humidity to permit the second amplifier to provide an output signal which varies linearly with percent relative humidity.

Relative humidity computer

A proportional plus integral controller connectable in a conventional proportional control loop of a process control system is selectively operable in a proportional only mode or a proportional plus integral mode in accordance with the positioning of a mode select switch and exhibits substantially bumpless forward transfer from proportional only to proportional plus integral operating modes.

Jon Harold Bechtel

Papers

Relative humidity computer

Insertion integrating controller