Department 6 - equipment - air conditioning

The respiration rate, measured with infrared gas sensors in enhanced method (accumulation of CO₂ in closed cuvettes), is used as measure for the activity of the produce metabolism.

Measurement of respiration rate of clementines

Based on the accumulation of CO₂ in the cuvettes the respiration rate (CO₂) of products to be examined is determined and transferred in an Excel work sheet realtime.

Current value and change of the respiration rate (CO₂) R = f(time [min])

The postharvest simulation for storage of horticultural produce in controlled atmosphere (CA-storage) is carried out in an experimental installation of closed cuvettes.

The tissue resistance in the water vapour pathway is determined by the difference in fresh matter per time interval, the surface temperature of the produce and ambient conditions in sufficient distance to the produce (air temperature, relative air humidity).

Measurement of an external degree of freshness in the case of peaches)

With the thermografic camera system surface temperature distributions on horticultural products are measured. Various temperature differences show different transpiration intensities (atmospheric evaporation effect).

Measurement of surface temperature distribution at natural convection (tomatoes)	Measurement of local transpiration differences on apples (stem and skin)

Surface temperatures of carrots after washing under different conditions (right two references, center two normal washed, left two intensively washed carrots)

In the air flow channel horticultural products as well as packages are subjected to defined environmental conditions (air temperature, air humidity, air velocity).


The installed sensors are connected to a data aquisition system. By means of heat and mass balances climate product properties and package properties are determined.

Inside the food display cabinet (in cooperation with Linde AG) with active air humidification a considerable increase of keeping quality of vegetables can be realised.

Food display cabinet based on atmospherical evaporation cooling in a Potsdamer REWE Market	Temperature distribution above vegetable containers under laboratory conditions

The keeping quality of fruit (cherries) is increased as a result of quick cooling-down after harvest, rewarming after cooling and surface drying at wet climatic conditions.

Air flow around and against transport packaging units	80 cardboard cartons (Werder Frucht) of cherries in an opened conditioner

Horticultural Engineering

Air conditioning and maintenance of freshness