Mississippi State University
Purswell, Joseph L.
Ward, Jason K.
Davis, Jeremiah D.
Date of Degree
Dissertation - Open Access
Doctor of Philosophy
College of Agriculture and Life Sciences
Department of Agricultural and Biological Engineering
Broiler production requires significant expenditures for heating fuel year round. Poor thermal envelope performance leads to reduced live performance, increased energy use, and reduced profitability. Poultry house building component thermal resistance (R-value) is subject to change over time. To characterize the thermal envelope heat transmission and building component R-value of two broiler houses of different ages, conductive heat flux (W/m2) and temperature gradient (Delta T °C) were monitored with heat flux meter (HFM) arrays and temperature sensors over a 13-month period. Net heat loss and building component (walls and ceiling) thermal resistance were determined from the data. Results showed differences in net heat loss were observed for the ceiling zones where 84% more heat was lost through the ceiling of the older house than that of the newer house (P < 0.05). R-values determined from field measurements for both houses were below estimated theoretical composite R-values. Observed R-values were greater for ceiling envelope zones of the newer house when compared to the older house. Increased heat loss and reductions in ceiling envelope zone R-values for the older house were attributed to shifting and settling of the looseill cellulose attic insulation material, which was especially prevalent at the ceiling peak zone. To verify the feasibility of using sol-air temperature in lieu of outside air temperature to account for radiant load during warm conditions, field measurements of temperature (°C) (interior air, exterior air, and exterior surface) and solar radiation (W/m2) were recorded of a broiler house. Sol-air temperatures were calculated from these data. Observed maximum daily air temperatures were significantly different (P<0.0001) from maximum surface and sol-air temperatures. Maximum surface and sol-air temperatures were not significantly different (P=0.2144, P=0.1544). Simulations of conductive heat transfer by air and sol-air temperatures using climatic data showed heat gain as calculated by sol-air Delta T was considerably higher when compared to heat gain calculated by air Delta T. This study supports the rationale that the sol-air temperature concept results in improved estimates of conductive heat transfer during daytime conditions which can be used to optimize insulation and ventilation requirements for broiler houses during warm conditions.
Chesser, Gary Daniel, "Monitoring of Conductance Heat Transfer Through the Thermal Envelope of a Commercial Broiler Production House in Situ" (2017). Theses and Dissertations. 3197.