tailieunhanh - ENERGY MANAGEMENT HANDBOOKS phần 4

Hình 10,13 ướt phía sơ đồ sơ đồ kiệm. xây dựng các nhân viên phục vụ. Ví dụ, các điều khiển trên một máy thông gió đơn vị bao gồm một nhiệt nhiệt độ trong phòng điều khiển van cuộn dây sưởi ấm hoặc làm mát, điều khiển van điều tiết điều chỉnh tỷ lệ không khí trong lành trộn với không khí phòng tái tuần hoàn, | HVAC Systems 265 Figure Wet-side economizer schematic diagram. building service personnel. For example the controls on a unit ventilator include a room temperature thermostat which controls the valve on the heating or cooling coil a damper control which adjusts the proportion of fresh air mixed with recirculated room air and a low-limit thermostat which prevents the temperature of outside air from dropping below a preset temperature usually 55 to 60 F 13 to 16 C . A common error of occupants or building custodians in response to a sense that the air supplied by the unit ventilator is too cold is to increase the setpoint on the low-limit thermostat which prevents free cooling from outside air or on systems without a cooling coil prevents cooling altogether. Controls which are subject to misadjustment by building occupants should be placed so that they cannot be tampered with. The energy consumption of thermally heavy buildings is less related to either the inside or outside air temperature. Both the heating and cooling loads in thermally heavy buildings are heavily dependent on the heat generated from internal loads and the thermal energy stored in the building mass which may be dis 266 Energy Management Handbook sipated at a later time. In an indirect control system the amount of energy consumed is not a function of human thermal comfort needs but of other factors such as outdoor temperature humidity or enthalpy. Indirect control systems determine the set points for cool air temperature water temperatures etc. As a result indirect control systems tend to adjust themselves for peak conditions rather than actual conditions. This leads to overheating or overcooling of spaces with less than peak loads. One of the most serious threats to the efficiency of any system is the need to heat and cool air or water simultaneously in order to achieve the thermal balance required for adequate conditioning of spaces. Figure indicates that 20 percent of the energy .