Cold Room Heat Load
Compute the product cooling heat load in a cold room, Q = m·cp·ΔT, from the product mass, its specific heat and the desired temperature change. It is the sensible-heat portion to remove to lower the product temperature — one of the components of the room's total load (which also includes wall transmission, infiltration, lighting, motors and people). It defines the refrigerating capacity needed. Enter the mass, the specific heat and the ΔT.
Result
—
Cold room heat load
Sizing a cold room starts by adding up every source of heat the refrigeration system will have to remove. One of the main ones is the product load: the sensible heat needed to bring the goods down in temperature, Q = m·cp·ΔT, a function of the mass, the specific heat of the product and the required temperature change. Cooling one tonne of fruit from 25 °C to 5 °C, for example, means removing a considerable amount of energy — and doing it within a reasonable time is what sets the capacity required. But the product load is only one of the terms. The total heat load of the room further adds: heat transmission through walls, ceiling and floor (Q = U·A·ΔT through the insulated envelope); infiltration of warm air whenever doors open; the heat released by lighting, fan motors and people working inside; the latent heat of freezing (if the product changes phase) and even the heat of respiration of living fruit and vegetables. For frozen goods, below the freezing point, the latent heat of ice dominates. Undersizing the load leaves a room that never reaches temperature; oversizing wastes capital and energy. This calculator covers the sensible heat term of the product. Enter the mass, the specific heat and the ΔT.
Related Tools
Food Specific Heat (Choi-Okos)
Compute a food's specific heat by the Choi-Okos equations, cp = 4.18·Xwater + 1.55·Xprotein + 1.71·Xfat + 1.42·Xcarbohydrate + 0.91·Xash (kJ/kg·K), from the component mass fractions. Since water has a very high specific heat, wetter foods heat and cool more slowly. It is essential in computing the heat loads of cooking, refrigeration and freezing. Enter the water, protein, fat, carbohydrate and ash fractions.
Pile Bearing Capacity
Calculate a pile's ultimate bearing capacity, Q_ult = Q_p + Q_l, summing the point (tip) resistance Q_p (kN) and the side (skin friction) resistance Q_l (kN). The pile is the DEEP foundation element used when surface soil lacks capacity for the structure's loads — it transfers loads to deeper, stronger subsoil layers. This transfer occurs by TWO mechanisms acting at once: TIP resistance (the pile bears on a firm layer at its base, like a column, mobilizing the soil resistance under the tip) and SIDE resistance (friction and adhesion between the pile's lateral surface and surrounding soil, along its whole length). Their proportion defines the behavior: END-bearing piles (crossing soft soil to bear on rock or firm soil) work mainly by the tip; FLOATING or friction piles (driven in homogeneous soil, no firm layer) work mainly by side friction. The ultimate capacity, divided by a safety factor (typically 2), gives the design allowable load. Determining Q_p and Q_l — by theoretical formulas, SPT-based semi-empirical methods (Aoki-Velloso, Décourt-Quaresma) or load tests — is the central deep-foundation design calculation. Enter the tip resistance and the side resistance.
Brake Power Dissipated
Calculate the power dissipated by a brake under torque, P = T·(2π·n/60), from the braking torque T (N·m) and the rotation n (rpm). Dissipated power is the rate at which the brake converts mechanical energy to heat — the product of braking torque and angular velocity. It differs from total braking ENERGY: energy is the total heat generated (joules), while power is the INTENSITY of that heat generation (watts), and it determines the brake's steady-state temperature. A brake dissipating much energy but slowly (low power) heats little; one dissipating the same energy fast (high power) heats much more. Dissipated power is critical in brakes working CONTINUOUSLY or repetitively: retention brakes on long descents, industrial equipment brakes (hoists, cranes, conveyors holding load), and dynamometers (which measure engine power precisely by dissipating it in a brake). There, the steady-state dissipated power sets the COOLING capacity needed (ventilation, water cooling) to keep temperature stable. Equating dissipated power to cooling capacity gives the equilibrium temperature. Enter the braking torque and the rotation.
WBGT (Occupational Heat Index)
Calculate the WBGT (wet bulb globe temperature) for indoor environments without solar load, WBGT = 0.7·t_nw + 0.3·t_g, from the natural wet-bulb temperature t_nw and the globe temperature t_g (°C). The result, in °C, is the heat stress index used to assess heat exposure: compared with tolerance limits according to the activity's metabolic rate, it sets the allowed work-rest regime. For environments with solar load, the dry-bulb temperature is also included. Enter the natural wet-bulb and globe temperatures.
Refrigerant Mass Flow
Compute the refrigerant mass flow needed in a cycle, ṁ = refrigerating capacity / refrigerating effect, dividing the desired cooling load (kW) by the specific refrigerating effect (kJ/kg, the enthalpy absorbed per kilo at the evaporator). It is how much refrigerant must circulate per second to meet the demand — the basis for sizing the compressor, the piping and the system gas charge. Enter the refrigerating capacity and the refrigerating effect.
Compressor Volumetric Displacement
Compute the volumetric displacement of a reciprocating compressor, Vd = (π/4)·D²·L·n, the volume swept by the pistons, from the cylinder bore (D), the stroke (L) and the number of cylinders (n). It is the compressor's 'displacement' — the theoretical volume aspirated per revolution, which, multiplied by the speed and the volumetric efficiency, gives the actual flow. It defines the compressor capacity. Enter the bore, the stroke and the number of cylinders.
The results provided by this tool are for general informational and educational purposes only and do not constitute professional, financial, medical, legal, tax or accounting advice. Always confirm important decisions with a qualified professional and official sources.