The efficiency of the heat pump included in the greenhouse heating system

anglais. Objects with the horticultural production have a specific heat demand that is mostly dependent on the solar conditions. With low outdoor temperatures but high solar radiation intensity a large heat surpluses in greenhouses are generated. They are released into the atmosphere through ventilation system (Rutkowski, Wojciech, 2009). Simultaneously, if the gardening production is carried on there is a high heat demand for process water heating. Therefore, the goal of the study was to measure and exploit heat excess directly in the production process. To better use the heat surpluses the heat pump was integrated into the recovery system. Inclusion a heat pump into the system allows wider use of the effect, which is higher water temperature. Water with a higher temperature after mixing can be used for fertigation or as a heat accumulator in the greenhouse heating process. In specific outside climate conditions the object‘s energy balance was carried and the energy amount loses through ventilation system were determined. A heat exchanger installed in the ventilation system was the lower heat pump source, which supplied hot water tank. The energy excess that occur on the upper source of heat pump, allows at the same time the energy accumulation and heating an object at the period of the increased demand (Rutkowski, Wojciech, 2009). The heat pump as an auxiliary energy source allows covering partially the heat demands during rush periods and in large part solves the energy problems for process water heating. An important factor in combined heat and power system is the proper selection of system components. An adequate heat pump power, a matched buffer tank capacity and the way of use the energy stream from ventilation system have a significant impact on the energy and economic efficiency of the system.

anglais. heating system, pump, greenhouse

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552-556