Environmental test chamber with uniform airflow

A method of testing a response of a unit-under-test to treated air in an environmental test chamber, comprising:

• the environmental test chamber having a housing, an airflow plenum and an air treatment system, said housing having an enclosing wall defining a test bay with an access opening in said wall providing access to said test bay and a closure selectively covering said opening, said airflow plenum supplying treated air to said test bay and said air treatment system treating air flowing through said plenum;
• and
• operating said air treatment system to flow treated air through said plenum in two selective modes, wherein said air treatment system flows treated air in a first flow direction through the unit-under-test in one of said modes and flows air in a second flow direction through the unit-under-test in a second of said modes, wherein said first and second flow directions being different from each other, including selecting the mode of operating the air treatment system based at least in part upon orientation in the test bay of the unit-under-test.

A refrigeration system for use in an environmental test chamber having a housing with an enclosing wall defining a test bay with an access opening in said wall providing access to said test bay and a closure selectively covering said opening, an airflow plenum supplying treated air to said test bay, an air treatment system treating air flowing through said plenum and a control, said control operating said air treatment system to flow treated air through said plenum in two selective modes, wherein said air treatment system flows treated air in a first flow direction through said test bay in one of the modes and flows air in a second flow direction through said test bay in a second of the modes, wherein said first and second flow directions being different from each other, wherein said air treatment system includes a refrigeration system, said refrigeration system comprising:

• an evaporator coil and a fluid circuit for routing refrigerant through said evaporator coil, wherein said fluid circuit includes a first fluid circuit portion that is configured to optimize cooling of air flowing one direction through said evaporator coil and a second fluid circuit portion that is configured to optimize cooling of air flowing a second opposite direction through said evaporator coil.